21972132 has 144 divisors (see below), whose sum is σ = 72159360. Its totient is φ = 5474304.

The previous prime is 21972127. The next prime is 21972173. The reversal of 21972132 is 23127912.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21972096 and 21972105.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 62068 + ... + 62420.

Almost surely, 2^21972132 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 21972132, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36079680).

21972132 is an abundant number, since it is smaller than the sum of its proper divisors (50187228).

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

21972132 is a wasteful number, since it uses less digits than its factorization.

21972132 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402 (or 397 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21972132 is about 4687.4440796664. Note that the first 3 decimals coincide. The cubic root of 21972132 is about 280.0855690852.

The spelling of 21972132 in words is "twenty-one million, nine hundred seventy-two thousand, one hundred thirty-two".