20465640 has 96 divisors (see below), whose sum is σ = 71646120. Its totient is φ = 5036544.

The previous prime is 20465609. The next prime is 20465647. The reversal of 20465640 is 4656402.

It is a happy number.

20465640 is a `hidden beast` number, since 2 + 0 + 4 + 656 + 4 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 13527684 + 6937956 = 3678^2 + 2634^2 .

It is not an unprimeable number, because it can be changed into a prime (20465647) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2494 + ... + 6866.

Almost surely, 2^20465640 is an apocalyptic number.

20465640 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 20465640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35823060).

20465640 is an abundant number, since it is smaller than the sum of its proper divisors (51180480).

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

20465640 is a wasteful number, since it uses less digits than its factorization.

20465640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4403 (or 4396 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 20465640 is about 4523.8965505414. The cubic root of 20465640 is about 273.5321905412.

The spelling of 20465640 in words is "twenty million, four hundred sixty-five thousand, six hundred forty".