21531157733 has 4 divisors (see below), whose sum is σ = 21989267520. Its totient is φ = 21073047948.

The previous prime is 21531157691. The next prime is 21531157741. The reversal of 21531157733 is 33775113512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21531157733 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 (21531157783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 229054823 + ... + 229054916.

It is an arithmetic number, because the mean of its divisors is an integer number (5497316880).

Almost surely, 2^21531157733 is an apocalyptic number.

It is an amenable number.

21531157733 is a deficient number, since it is larger than the sum of its proper divisors (458109787).

21531157733 is an equidigital number, since it uses as much as digits as its factorization.

21531157733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458109786.

The product of its digits is 66150, while the sum is 38.

The spelling of 21531157733 in words is "twenty-one billion, five hundred thirty-one million, one hundred fifty-seven thousand, seven hundred thirty-three".