21917390724 has 96 divisors (see below), whose sum is σ = 59482644480. Its totient is φ = 6970471200.

The previous prime is 21917390687. The next prime is 21917390731. The reversal of 21917390724 is 42709371912.

21917390724 is a `hidden beast` number, since 2 + 191 + 7 + 390 + 72 + 4 = 666.

It is a super-2 number, since 2×21917390724² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21917390724.

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, 191607 + ... + 283809.

It is an arithmetic number, because the mean of its divisors is an integer number (619610880).

Almost surely, 2^21917390724 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 21917390724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29741322240).

21917390724 is an abundant number, since it is smaller than the sum of its proper divisors (37565253756).

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

21917390724 is a wasteful number, since it uses less digits than its factorization.

21917390724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92318 (or 92310 counting only the distinct ones).

The product of its (nonzero) digits is 190512, while the sum is 45.

The spelling of 21917390724 in words is "twenty-one billion, nine hundred seventeen million, three hundred ninety thousand, seven hundred twenty-four".