20402320 has 40 divisors (see below), whose sum is σ = 47731320. Its totient is φ = 8110080.

The previous prime is 20402287. The next prime is 20402321. The reversal of 20402320 is 2320402.

It can be written as a sum of positive squares in 4 ways, for example, as 2458624 + 17943696 = 1568^2 + 4236^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×20402320² = 832509322764800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20402320.

It is not an unprimeable number, because it can be changed into a prime (20402321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13776 + ... + 15184.

It is an arithmetic number, because the mean of its divisors is an integer number (1193283).

Almost surely, 2^20402320 is an apocalyptic number.

20402320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20402320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23865660).

20402320 is an abundant number, since it is smaller than the sum of its proper divisors (27329000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20402320 is a wasteful number, since it uses less digits than its factorization.

20402320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1603 (or 1597 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 13.

The square root of 20402320 is about 4516.8927372697. The cubic root of 20402320 is about 273.2497993133.

Adding to 20402320 its reverse (2320402), we get a palindrome (22722722).

The spelling of 20402320 in words is "twenty million, four hundred two thousand, three hundred twenty".