21407015664 has 100 divisors (see below), whose sum is σ = 62073438504. Its totient is φ = 7122390912.

The previous prime is 21407015659. The next prime is 21407015677. The reversal of 21407015664 is 46651070412.

21407015664 is a `hidden beast` number, since 21 + 4 + 0 + 70 + 1 + 566 + 4 = 666.

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 19 ways as a sum of consecutive naturals, for example, 693814 + ... + 724010.

Almost surely, 2^21407015664 is an apocalyptic number.

21407015664 is a gapful number since it is divisible by the number (24) 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 21407015664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31036719252).

21407015664 is an abundant number, since it is smaller than the sum of its proper divisors (40666422840).

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

21407015664 is a wasteful number, since it uses less digits than its factorization.

21407015664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30764 (or 30749 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 21407015664 in words is "twenty-one billion, four hundred seven million, fifteen thousand, six hundred sixty-four".