20656440 has 144 divisors (see below), whose sum is σ = 78160680. Its totient is φ = 4717440.

The previous prime is 20656429. The next prime is 20656451. The reversal of 20656440 is 4465602.

It is a happy number.

20656440 is a `hidden beast` number, since 2 + 0 + 656 + 4 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (20656429) and next prime (20656451).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 17055 + ... + 18225.

Almost surely, 2^20656440 is an apocalyptic number.

20656440 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 20656440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39080340).

20656440 is an abundant number, since it is smaller than the sum of its proper divisors (57504240).

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

20656440 is a wasteful number, since it uses less digits than its factorization.

20656440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1202 (or 1188 counting only the distinct ones).

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

The square root of 20656440 is about 4544.9356431087. The cubic root of 20656440 is about 274.3796042039.

The spelling of 20656440 in words is "twenty million, six hundred fifty-six thousand, four hundred forty".