165721672250 has 16 divisors (see below), whose sum is σ = 310230970920. Its totient is φ = 66288668800.

The previous prime is 165721672243. The next prime is 165721672283. The reversal of 165721672250 is 52276127561.

It can be written as a sum of positive squares in 4 ways, for example, as 57928306489 + 107793365761 = 240683^2 + 328319^2 .

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, 331443095 + ... + 331443594.

Almost surely, 2^165721672250 is an apocalyptic number.

165721672250 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

165721672250 is a deficient number, since it is larger than the sum of its proper divisors (144509298670).

165721672250 is an equidigital number, since it uses as much as digits as its factorization.

165721672250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662886706 (or 662886696 counting only the distinct ones).

The product of its (nonzero) digits is 352800, while the sum is 44.

The spelling of 165721672250 in words is "one hundred sixty-five billion, seven hundred twenty-one million, six hundred seventy-two thousand, two hundred fifty".