21137870520 has 192 divisors, whose sum is σ = 74090933280. Its totient is φ = 5195547648.

The previous prime is 21137870503. The next prime is 21137870539. The reversal of 21137870520 is 2507873112.

21137870520 is a `hidden beast` number, since 21 + 1 + 37 + 87 + 0 + 520 = 666.

It is a super-3 number, since 3×21137870520³ (a number of 32 digits) contains 333 as substring.

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 47 ways as a sum of consecutive naturals, for example, 3614719 + ... + 3620561.

Almost surely, 2^21137870520 is an apocalyptic number.

21137870520 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 21137870520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37045466640).

21137870520 is an abundant number, since it is smaller than the sum of its proper divisors (52953062760).

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

21137870520 is a wasteful number, since it uses less digits than its factorization.

21137870520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6646 (or 6639 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The spelling of 21137870520 in words is "twenty-one billion, one hundred thirty-seven million, eight hundred seventy thousand, five hundred twenty".