165521631 has 8 divisors (see below), whose sum is σ = 240758784. Its totient is φ = 100316120.

The previous prime is 165521591. The next prime is 165521641. The reversal of 165521631 is 136125561.

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 165521631 - 2⁹ = 165521119 is a prime.

It is a super-2 number, since 2×165521631² = 54794820657800322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165521641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2507871 + ... + 2507936.

It is an arithmetic number, because the mean of its divisors is an integer number (30094848).

Almost surely, 2^165521631 is an apocalyptic number.

165521631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

165521631 is a deficient number, since it is larger than the sum of its proper divisors (75237153).

165521631 is a wasteful number, since it uses less digits than its factorization.

165521631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5015821.

The product of its digits is 5400, while the sum is 30.

The square root of 165521631 is about 12865.5210154894. The cubic root of 165521631 is about 549.0580361405.

The spelling of 165521631 in words is "one hundred sixty-five million, five hundred twenty-one thousand, six hundred thirty-one".