21756299136 has 128 divisors (see below), whose sum is σ = 67893517440. Its totient is φ = 6085662720.

The previous prime is 21756299099. The next prime is 21756299137. The reversal of 21756299136 is 63199265712.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×21756299136² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21756299137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143190 + ... + 253013.

It is an arithmetic number, because the mean of its divisors is an integer number (530418105).

Almost surely, 2^21756299136 is an apocalyptic number.

21756299136 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21756299136 is an abundant number, since it is smaller than the sum of its proper divisors (46137218304).

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

21756299136 is a wasteful number, since it uses less digits than its factorization.

21756299136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396244 (or 396232 counting only the distinct ones).

The product of its digits is 1224720, while the sum is 51.

The spelling of 21756299136 in words is "twenty-one billion, seven hundred fifty-six million, two hundred ninety-nine thousand, one hundred thirty-six".