21254991531 has 8 divisors (see below), whose sum is σ = 28347890640. Its totient is φ = 14166043392.

The previous prime is 21254991529. The next prime is 21254991551. The reversal of 21254991531 is 13519945212.

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

It is not a de Polignac number, because 21254991531 - 2¹ = 21254991529 is a prime.

It is a super-2 number, since 2×21254991531² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21254991551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 975166 + ... + 996723.

It is an arithmetic number, because the mean of its divisors is an integer number (3543486330).

Almost surely, 2^21254991531 is an apocalyptic number.

21254991531 is a deficient number, since it is larger than the sum of its proper divisors (7092899109).

21254991531 is a wasteful number, since it uses less digits than its factorization.

21254991531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1975485.

The product of its digits is 97200, while the sum is 42.

The spelling of 21254991531 in words is "twenty-one billion, two hundred fifty-four million, nine hundred ninety-one thousand, five hundred thirty-one".