21972878 has 8 divisors (see below), whose sum is σ = 33267672. Its totient is φ = 10883656.

The previous prime is 21972869. The next prime is 21972901. The reversal of 21972878 is 87827912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51125 + ... + 51552.

It is an arithmetic number, because the mean of its divisors is an integer number (4158459).

Almost surely, 2^21972878 is an apocalyptic number.

21972878 is a deficient number, since it is larger than the sum of its proper divisors (11294794).

21972878 is a wasteful number, since it uses less digits than its factorization.

21972878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102786.

The product of its digits is 112896, while the sum is 44.

The square root of 21972878 is about 4687.5236532737. The cubic root of 21972878 is about 280.0887388803.

The spelling of 21972878 in words is "twenty-one million, nine hundred seventy-two thousand, eight hundred seventy-eight".