21023532756 has 288 divisors, whose sum is σ = 60055224320. Its totient is φ = 6172588800.

The previous prime is 21023532721. The next prime is 21023532767. The reversal of 21023532756 is 65723532012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21023532756.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 99637491 + ... + 99637701.

Almost surely, 2^21023532756 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 21023532756, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30027612160).

21023532756 is an abundant number, since it is smaller than the sum of its proper divisors (39031691564).

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

21023532756 is a wasteful number, since it uses less digits than its factorization.

21023532756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435 (or 430 counting only the distinct ones).

The product of its (nonzero) digits is 75600, while the sum is 36.

The spelling of 21023532756 in words is "twenty-one billion, twenty-three million, five hundred thirty-two thousand, seven hundred fifty-six".