21255308620 has 96 divisors (see below), whose sum is σ = 54983569536. Its totient is φ = 6721228800.

The previous prime is 21255308611. The next prime is 21255308687. The reversal of 21255308620 is 2680355212.

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 31 ways as a sum of consecutive naturals, for example, 2472730 + ... + 2481310.

It is an arithmetic number, because the mean of its divisors is an integer number (572745516).

Almost surely, 2^21255308620 is an apocalyptic number.

21255308620 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 21255308620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27491784768).

21255308620 is an abundant number, since it is smaller than the sum of its proper divisors (33728260916).

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

21255308620 is a wasteful number, since it uses less digits than its factorization.

21255308620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9971 (or 9969 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 34.

The spelling of 21255308620 in words is "twenty-one billion, two hundred fifty-five million, three hundred eight thousand, six hundred twenty".