21533312531 has 4 divisors (see below), whose sum is σ = 22799977992. Its totient is φ = 20266647072.

The previous prime is 21533312527. The next prime is 21533312533. The reversal of 21533312531 is 13521333512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21533312531 - 2² = 21533312527 is a prime.

It is a super-2 number, since 2×21533312531² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21533312494 and 21533312503.

It is not an unprimeable number, because it can be changed into a prime (21533312533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 633332705 + ... + 633332738.

It is an arithmetic number, because the mean of its divisors is an integer number (5699994498).

Almost surely, 2^21533312531 is an apocalyptic number.

21533312531 is a deficient number, since it is larger than the sum of its proper divisors (1266665461).

21533312531 is a wasteful number, since it uses less digits than its factorization.

21533312531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1266665460.

The product of its digits is 8100, while the sum is 29.

The spelling of 21533312531 in words is "twenty-one billion, five hundred thirty-three million, three hundred twelve thousand, five hundred thirty-one".