21151733621 has 4 divisors (see below), whose sum is σ = 21244099500. Its totient is φ = 21059367744.

The previous prime is 21151733609. The next prime is 21151733623. The reversal of 21151733621 is 12633715112.

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 20081724100 + 1070009521 = 141710^2 + 32711^2 .

It is a cyclic number.

It is not a de Polignac number, because 21151733621 - 2¹⁸ = 21151471477 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 (21151733623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46182596 + ... + 46183053.

It is an arithmetic number, because the mean of its divisors is an integer number (5311024875).

Almost surely, 2^21151733621 is an apocalyptic number.

It is an amenable number.

21151733621 is a deficient number, since it is larger than the sum of its proper divisors (92365879).

21151733621 is an equidigital number, since it uses as much as digits as its factorization.

21151733621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92365878.

The product of its digits is 7560, while the sum is 32.

The spelling of 21151733621 in words is "twenty-one billion, one hundred fifty-one million, seven hundred thirty-three thousand, six hundred twenty-one".