21513134640 has 160 divisors (see below), whose sum is σ = 70472632320. Its totient is φ = 5417837568.

The previous prime is 21513134603. The next prime is 21513134729. The reversal of 21513134640 is 4643131512.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21513134598 and 21513134607.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 411414 + ... + 460746.

It is an arithmetic number, because the mean of its divisors is an integer number (440453952).

Almost surely, 2^21513134640 is an apocalyptic number.

21513134640 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 21513134640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35236316160).

21513134640 is an abundant number, since it is smaller than the sum of its proper divisors (48959497680).

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

21513134640 is a wasteful number, since it uses less digits than its factorization.

21513134640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49451 (or 49445 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The spelling of 21513134640 in words is "twenty-one billion, five hundred thirteen million, one hundred thirty-four thousand, six hundred forty".