21332015561 has 4 divisors (see below), whose sum is σ = 21390141312. Its totient is φ = 21273889812.

The previous prime is 21332015539. The next prime is 21332015563. The reversal of 21332015561 is 16551023312.

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 not a de Polignac number, because 21332015561 - 2³⁴ = 4152146377 is a prime.

It is a super-2 number, since 2×21332015561² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21332015563) 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, 29062325 + ... + 29063058.

It is an arithmetic number, because the mean of its divisors is an integer number (5347535328).

Almost surely, 2^21332015561 is an apocalyptic number.

It is an amenable number.

21332015561 is a deficient number, since it is larger than the sum of its proper divisors (58125751).

21332015561 is an equidigital number, since it uses as much as digits as its factorization.

21332015561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58125750.

The product of its (nonzero) digits is 5400, while the sum is 29.

Adding to 21332015561 its reverse (16551023312), we get a palindrome (37883038873).

The spelling of 21332015561 in words is "twenty-one billion, three hundred thirty-two million, fifteen thousand, five hundred sixty-one".