21356745732 has 144 divisors (see below), whose sum is σ = 63968486400. Its totient is φ = 5878252800.

The previous prime is 21356745713. The next prime is 21356745779. The reversal of 21356745732 is 23754765312.

21356745732 is a `hidden beast` number, since 2 + 1 + 3 + 5 + 6 + 74 + 573 + 2 = 666.

It is a super-2 number, since 2×21356745732² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3497482 + ... + 3503582.

It is an arithmetic number, because the mean of its divisors is an integer number (444225600).

Almost surely, 2^21356745732 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21356745732, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31984243200).

21356745732 is an abundant number, since it is smaller than the sum of its proper divisors (42611740668).

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

21356745732 is a wasteful number, since it uses less digits than its factorization.

21356745732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6626 (or 6621 counting only the distinct ones).

The product of its digits is 1058400, while the sum is 45.

The spelling of 21356745732 in words is "twenty-one billion, three hundred fifty-six million, seven hundred forty-five thousand, seven hundred thirty-two".