165721245 has 16 divisors (see below), whose sum is σ = 265493760. Its totient is φ = 88271424.

The previous prime is 165721229. The next prime is 165721267. The reversal of 165721245 is 542127561.

165721245 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165721245 - 2⁴ = 165721229 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5772 + ... + 19098.

It is an arithmetic number, because the mean of its divisors is an integer number (16593360).

Almost surely, 2^165721245 is an apocalyptic number.

165721245 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

165721245 is a deficient number, since it is larger than the sum of its proper divisors (99772515).

165721245 is a wasteful number, since it uses less digits than its factorization.

165721245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14164.

The product of its digits is 16800, while the sum is 33.

The square root of 165721245 is about 12873.2763894822. The cubic root of 165721245 is about 549.2786631803.

The spelling of 165721245 in words is "one hundred sixty-five million, seven hundred twenty-one thousand, two hundred forty-five".