21972278 has 8 divisors (see below), whose sum is σ = 33129768. Its totient is φ = 10929024.

The previous prime is 21972277. The next prime is 21972281. The reversal of 21972278 is 87227912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21972271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28076 + ... + 28847.

It is an arithmetic number, because the mean of its divisors is an integer number (4141221).

Almost surely, 2^21972278 is an apocalyptic number.

21972278 is a deficient number, since it is larger than the sum of its proper divisors (11157490).

21972278 is a wasteful number, since it uses less digits than its factorization.

21972278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57118.

The product of its digits is 28224, while the sum is 38.

The square root of 21972278 is about 4687.4596531597. The cubic root of 21972278 is about 280.0861894529.

The spelling of 21972278 in words is "twenty-one million, nine hundred seventy-two thousand, two hundred seventy-eight".