21132170165 has 8 divisors (see below), whose sum is σ = 25359389880. Its totient is φ = 16905212352.

The previous prime is 21132170153. The next prime is 21132170209. The reversal of 21132170165 is 56107123112.

It can be written as a sum of positive squares in 4 ways, for example, as 45064369 + 21087105796 = 6713^2 + 145214^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21132170165 - 2⁴ = 21132170149 is a prime.

It is a super-2 number, since 2×21132170165² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 251927 + ... + 325163.

It is an arithmetic number, because the mean of its divisors is an integer number (3169923735).

Almost surely, 2^21132170165 is an apocalyptic number.

It is an amenable number.

21132170165 is a deficient number, since it is larger than the sum of its proper divisors (4227219715).

21132170165 is an equidigital number, since it uses as much as digits as its factorization.

21132170165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130951.

The product of its (nonzero) digits is 2520, while the sum is 29.

Adding to 21132170165 its reverse (56107123112), we get a palindrome (77239293277).

The spelling of 21132170165 in words is "twenty-one billion, one hundred thirty-two million, one hundred seventy thousand, one hundred sixty-five".