165720851 has 4 divisors (see below), whose sum is σ = 167269752. Its totient is φ = 164171952.

The previous prime is 165720833. The next prime is 165720853. The reversal of 165720851 is 158027561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165720851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165720853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 774290 + ... + 774503.

It is an arithmetic number, because the mean of its divisors is an integer number (41817438).

Almost surely, 2^165720851 is an apocalyptic number.

165720851 is a deficient number, since it is larger than the sum of its proper divisors (1548901).

165720851 is a wasteful number, since it uses less digits than its factorization.

165720851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1548900.

The product of its (nonzero) digits is 16800, while the sum is 35.

The square root of 165720851 is about 12873.2610864536. The cubic root of 165720851 is about 549.2782278791.

The spelling of 165720851 in words is "one hundred sixty-five million, seven hundred twenty thousand, eight hundred fifty-one".