21566898240 has 56 divisors (see below), whose sum is σ = 68474904960. Its totient is φ = 5751172608.

The previous prime is 21566898209. The next prime is 21566898257. The reversal of 21566898240 is 4289866512.

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, 11231800 + ... + 11233719.

It is an arithmetic number, because the mean of its divisors is an integer number (1222766160).

Almost surely, 2^21566898240 is an apocalyptic number.

21566898240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21566898240 is an abundant number, since it is smaller than the sum of its proper divisors (46908006720).

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

21566898240 is a wasteful number, since it uses less digits than its factorization.

21566898240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22465539 (or 22465529 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 51.

The spelling of 21566898240 in words is "twenty-one billion, five hundred sixty-six million, eight hundred ninety-eight thousand, two hundred forty".