20402240 has 56 divisors (see below), whose sum is σ = 49133760. Its totient is φ = 8068608.

The previous prime is 20402233. The next prime is 20402251. The reversal of 20402240 is 4220402.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32651 + ... + 33269.

Almost surely, 2^20402240 is an apocalyptic number.

20402240 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 20402240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24566880).

20402240 is an abundant number, since it is smaller than the sum of its proper divisors (28731520).

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

20402240 is a wasteful number, since it uses less digits than its factorization.

20402240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 739 (or 729 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 14.

The square root of 20402240 is about 4516.8838816157. The cubic root of 20402240 is about 273.2494421642.

Adding to 20402240 its reverse (4220402), we get a palindrome (24622642).

The spelling of 20402240 in words is "twenty million, four hundred two thousand, two hundred forty".