165551055561 has 48 divisors (see below), whose sum is σ = 256129689088. Its totient is φ = 102848486400.

The previous prime is 165551055451. The next prime is 165551055583. The reversal of 165551055561 is 165550155561.

It is not a de Polignac number, because 165551055561 - 2²⁶ = 165483946697 is a prime.

It is a super-2 number, since 2×165551055561² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165551055661) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 918666 + ... + 1083996.

Almost surely, 2^165551055561 is an apocalyptic number.

It is an amenable number.

165551055561 is a deficient number, since it is larger than the sum of its proper divisors (90578633527).

165551055561 is a wasteful number, since it uses less digits than its factorization.

165551055561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165502 (or 165499 counting only the distinct ones).

The product of its (nonzero) digits is 562500, while the sum is 45.

The spelling of 165551055561 in words is "one hundred sixty-five billion, five hundred fifty-one million, fifty-five thousand, five hundred sixty-one".