21210577920 has 704 divisors, whose sum is σ = 89986775040. Its totient is φ = 4632477696.

The previous prime is 21210577907. The next prime is 21210577937. The reversal of 21210577920 is 2977501212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 22256164 + ... + 22257116.

Almost surely, 2^21210577920 is an apocalyptic number.

21210577920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21210577920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44993387520).

21210577920 is an abundant number, since it is smaller than the sum of its proper divisors (68776197120).

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

21210577920 is a wasteful number, since it uses less digits than its factorization.

21210577920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1017 (or 993 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 36.

The spelling of 21210577920 in words is "twenty-one billion, two hundred ten million, five hundred seventy-seven thousand, nine hundred twenty".