21947157 has 12 divisors (see below), whose sum is σ = 32439264. Its totient is φ = 14290920.

The previous prime is 21947117. The next prime is 21947161. The reversal of 21947157 is 75174912.

It is a happy number.

It is not a de Polignac number, because 21947157 - 2¹⁶ = 21881621 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21947117) 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 11 ways as a sum of consecutive naturals, for example, 27969 + ... + 28742.

It is an arithmetic number, because the mean of its divisors is an integer number (2703272).

Almost surely, 2^21947157 is an apocalyptic number.

It is an amenable number.

21947157 is a deficient number, since it is larger than the sum of its proper divisors (10492107).

21947157 is a wasteful number, since it uses less digits than its factorization.

21947157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56760 (or 56757 counting only the distinct ones).

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

The square root of 21947157 is about 4684.7792904255. The cubic root of 21947157 is about 279.9794074992.

The spelling of 21947157 in words is "twenty-one million, nine hundred forty-seven thousand, one hundred fifty-seven".