161206551 has 16 divisors (see below), whose sum is σ = 260536320. Its totient is φ = 97700760.

The previous prime is 161206537. The next prime is 161206553. The reversal of 161206551 is 155602161.

It is a happy number.

161206551 is a `hidden beast` number, since 1 + 6 + 1 + 2 + 0 + 655 + 1 = 666.

It is not a de Polignac number, because 161206551 - 2⁵ = 161206519 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161206553) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 271095 + ... + 271688.

It is an arithmetic number, because the mean of its divisors is an integer number (16283520).

Almost surely, 2^161206551 is an apocalyptic number.

161206551 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161206551 is a deficient number, since it is larger than the sum of its proper divisors (99329769).

161206551 is a wasteful number, since it uses less digits than its factorization.

161206551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542803 (or 542797 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 161206551 is about 12696.7141812360. The cubic root of 161206551 is about 544.2447254856.

The spelling of 161206551 in words is "one hundred sixty-one million, two hundred six thousand, five hundred fifty-one".