21731337 has 6 divisors (see below), whose sum is σ = 31389722. Its totient is φ = 14487552.

The previous prime is 21731317. The next prime is 21731363. The reversal of 21731337 is 73313712.

It can be written as a sum of positive squares in only one way, i.e., 16842816 + 4888521 = 4104^2 + 2211^2 .

It is not a de Polignac number, because 21731337 - 2⁶ = 21731273 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21731337.

It is not an unprimeable number, because it can be changed into a prime (21731317) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207288 + ... + 1207305.

Almost surely, 2^21731337 is an apocalyptic number.

It is an amenable number.

21731337 is a deficient number, since it is larger than the sum of its proper divisors (9658385).

21731337 is a wasteful number, since it uses less digits than its factorization.

21731337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2414599 (or 2414596 counting only the distinct ones).

The product of its digits is 2646, while the sum is 27.

The square root of 21731337 is about 4661.6882135124. The cubic root of 21731337 is about 279.0586457055.

The spelling of 21731337 in words is "twenty-one million, seven hundred thirty-one thousand, three hundred thirty-seven".