21974157 has 6 divisors (see below), whose sum is σ = 31740462. Its totient is φ = 14649432.

The previous prime is 21974119. The next prime is 21974179. The reversal of 21974157 is 75147912.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15729156 + 6245001 = 3966^2 + 2499^2 .

It is not a de Polignac number, because 21974157 - 2¹⁵ = 21941389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21974107) 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 5 ways as a sum of consecutive naturals, for example, 1220778 + ... + 1220795.

It is an arithmetic number, because the mean of its divisors is an integer number (5290077).

Almost surely, 2^21974157 is an apocalyptic number.

It is an amenable number.

21974157 is a deficient number, since it is larger than the sum of its proper divisors (9766305).

21974157 is a wasteful number, since it uses less digits than its factorization.

21974157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2441579 (or 2441576 counting only the distinct ones).

The product of its digits is 17640, while the sum is 36.

The square root of 21974157 is about 4687.6600772667. The cubic root of 21974157 is about 280.0941732548.

The spelling of 21974157 in words is "twenty-one million, nine hundred seventy-four thousand, one hundred fifty-seven".