21530164640 has 96 divisors (see below), whose sum is σ = 55269527040. Its totient is φ = 7895577600.

The previous prime is 21530164567. The next prime is 21530164679. The reversal of 21530164640 is 4646103512.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21530164597 and 21530164606.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19991 + ... + 208470.

It is an arithmetic number, because the mean of its divisors is an integer number (575724240).

Almost surely, 2^21530164640 is an apocalyptic number.

21530164640 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 21530164640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27634763520).

21530164640 is an abundant number, since it is smaller than the sum of its proper divisors (33739362400).

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

21530164640 is a wasteful number, since it uses less digits than its factorization.

21530164640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228526 (or 228518 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 32.

The spelling of 21530164640 in words is "twenty-one billion, five hundred thirty million, one hundred sixty-four thousand, six hundred forty".