21168339291 has 24 divisors (see below), whose sum is σ = 33361975296. Its totient is φ = 12827064240.

The previous prime is 21168339287. The next prime is 21168339347. The reversal of 21168339291 is 19293386112.

It is a happy number.

21168339291 is a `hidden beast` number, since 21 + 1 + 6 + 8 + 339 + 291 = 666.

It is not a de Polignac number, because 21168339291 - 2² = 21168339287 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21168339211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 688146 + ... + 718248.

It is an arithmetic number, because the mean of its divisors is an integer number (1390082304).

Almost surely, 2^21168339291 is an apocalyptic number.

21168339291 is a deficient number, since it is larger than the sum of its proper divisors (12193636005).

21168339291 is a wasteful number, since it uses less digits than its factorization.

21168339291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37223 (or 37220 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The spelling of 21168339291 in words is "twenty-one billion, one hundred sixty-eight million, three hundred thirty-nine thousand, two hundred ninety-one".