21972924 has 48 divisors (see below), whose sum is σ = 58813440. Its totient is φ = 7086960.

The previous prime is 21972917. The next prime is 21972961. The reversal of 21972924 is 42927912.

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 15 ways as a sum of consecutive naturals, for example, 67 + ... + 6629.

It is an arithmetic number, because the mean of its divisors is an integer number (1225280).

Almost surely, 2^21972924 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 21972924, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29406720).

21972924 is an abundant number, since it is smaller than the sum of its proper divisors (36840516).

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

21972924 is a wasteful number, since it uses less digits than its factorization.

21972924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6607 (or 6599 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21972924 is about 4687.5285599130. The cubic root of 21972924 is about 280.0889343345.

The spelling of 21972924 in words is "twenty-one million, nine hundred seventy-two thousand, nine hundred twenty-four".