20815564400440 has 32 divisors (see below), whose sum is σ = 46835303382000. Its totient is φ = 8326175363584.

The previous prime is 20815564400357. The next prime is 20815564400441. The reversal of 20815564400440 is 4400446551802.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20815564400441) 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, 5509731 + ... + 8484589.

Almost surely, 2^{20815564400440} is an apocalyptic number.

20815564400440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20815564400440 is an abundant number, since it is smaller than the sum of its proper divisors (26019738981560).

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

20815564400440 is a wasteful number, since it uses less digits than its factorization.

20815564400440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3149799 (or 3149795 counting only the distinct ones).

The product of its (nonzero) digits is 614400, while the sum is 43.

The spelling of 20815564400440 in words is "twenty trillion, eight hundred fifteen billion, five hundred sixty-four million, four hundred thousand, four hundred forty".