21640930733 has 4 divisors (see below), whose sum is σ = 21677425308. Its totient is φ = 21604436160.

The previous prime is 21640930643. The next prime is 21640930747. The reversal of 21640930733 is 33703904612.

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 4657107049 + 16983823684 = 68243^2 + 130322^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21640930733 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 (21640930133) 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, 18246398 + ... + 18247583.

It is an arithmetic number, because the mean of its divisors is an integer number (5419356327).

Almost surely, 2^21640930733 is an apocalyptic number.

It is an amenable number.

21640930733 is a deficient number, since it is larger than the sum of its proper divisors (36494575).

21640930733 is an equidigital number, since it uses as much as digits as its factorization.

21640930733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36494574.

The product of its (nonzero) digits is 81648, while the sum is 38.

The spelling of 21640930733 in words is "twenty-one billion, six hundred forty million, nine hundred thirty thousand, seven hundred thirty-three".