21557045760 has 80 divisors (see below), whose sum is σ = 68915205216. Its totient is φ = 5748543488.

The previous prime is 21557045753. The next prime is 21557045761. The reversal of 21557045760 is 6754075512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21557045761) 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, 1395774 + ... + 1411133.

Almost surely, 2^21557045760 is an apocalyptic number.

21557045760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21557045760 is an abundant number, since it is smaller than the sum of its proper divisors (47358159456).

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

21557045760 is an equidigital number, since it uses as much as digits as its factorization.

21557045760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2806933 (or 2806917 counting only the distinct ones).

The product of its (nonzero) digits is 294000, while the sum is 42.

The spelling of 21557045760 in words is "twenty-one billion, five hundred fifty-seven million, forty-five thousand, seven hundred sixty".