21540024613 has 4 divisors (see below), whose sum is σ = 21677222380. Its totient is φ = 21402826848.

The previous prime is 21540024523. The next prime is 21540024691. The reversal of 21540024613 is 31642004512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4795147009 + 16744877604 = 69247^2 + 129402^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21540024613 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 (21540024113) 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, 68598648 + ... + 68598961.

It is an arithmetic number, because the mean of its divisors is an integer number (5419305595).

Almost surely, 2^21540024613 is an apocalyptic number.

It is an amenable number.

21540024613 is a deficient number, since it is larger than the sum of its proper divisors (137197767).

21540024613 is a wasteful number, since it uses less digits than its factorization.

21540024613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137197766.

The product of its (nonzero) digits is 5760, while the sum is 28.

The spelling of 21540024613 in words is "twenty-one billion, five hundred forty million, twenty-four thousand, six hundred thirteen".