21131513533 has 8 divisors (see below), whose sum is σ = 22781314808. Its totient is φ = 19485183744.

The previous prime is 21131513531. The next prime is 21131513539. The reversal of 21131513533 is 33531513112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2927567449 + 18203946084 = 54107^2 + 134922^2 .

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

It is not a de Polignac number, because 21131513533 - 2¹ = 21131513531 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131513531) 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, 855216 + ... + 879577.

It is an arithmetic number, because the mean of its divisors is an integer number (2847664351).

Almost surely, 2^21131513533 is an apocalyptic number.

It is an amenable number.

21131513533 is a deficient number, since it is larger than the sum of its proper divisors (1649801275).

21131513533 is a wasteful number, since it uses less digits than its factorization.

21131513533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735743.

The product of its digits is 4050, while the sum is 28.

The spelling of 21131513533 in words is "twenty-one billion, one hundred thirty-one million, five hundred thirteen thousand, five hundred thirty-three".