21540617500 has 30 divisors (see below), whose sum is σ = 47105027816. Its totient is φ = 8616246000.

The previous prime is 21540617489. The next prime is 21540617519. The reversal of 21540617500 is 571604512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4305624 + ... + 4310623.

Almost surely, 2^21540617500 is an apocalyptic number.

21540617500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21540617500 is an abundant number, since it is smaller than the sum of its proper divisors (25564410316).

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

21540617500 is an equidigital number, since it uses as much as digits as its factorization.

21540617500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8616271 (or 8616254 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 31.

The spelling of 21540617500 in words is "twenty-one billion, five hundred forty million, six hundred seventeen thousand, five hundred".