21538710417672 has 240 divisors, whose sum is σ = 69068035661040. Its totient is φ = 6062064490944.

The previous prime is 21538710417569. The next prime is 21538710417737. The reversal of 21538710417672 is 27671401783512.

21538710417672 is a `hidden beast` number, since 2 + 1 + 538 + 7 + 1 + 0 + 41 + 7 + 67 + 2 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 10652623 + ... + 12512225.

It is an arithmetic number, because the mean of its divisors is an integer number (287783481921).

Almost surely, 2^{21538710417672} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21538710417672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34534017830520).

21538710417672 is an abundant number, since it is smaller than the sum of its proper divisors (47529325243368).

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

21538710417672 is a wasteful number, since it uses less digits than its factorization.

21538710417672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1859710 (or 1859682 counting only the distinct ones).

The product of its (nonzero) digits is 3951360, while the sum is 54.

The spelling of 21538710417672 in words is "twenty-one trillion, five hundred thirty-eight billion, seven hundred ten million, four hundred seventeen thousand, six hundred seventy-two".