161031551 has 4 divisors (see below), whose sum is σ = 161190600. Its totient is φ = 160872504.

The previous prime is 161031547. The next prime is 161031553. The reversal of 161031551 is 155130161.

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

It is a cyclic number.

It is not a de Polignac number, because 161031551 - 2² = 161031547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161031553) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77996 + ... + 80033.

It is an arithmetic number, because the mean of its divisors is an integer number (40297650).

Almost surely, 2^161031551 is an apocalyptic number.

161031551 is a deficient number, since it is larger than the sum of its proper divisors (159049).

161031551 is a wasteful number, since it uses less digits than its factorization.

161031551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159048.

The product of its (nonzero) digits is 450, while the sum is 23.

The square root of 161031551 is about 12689.8207631156. The cubic root of 161031551 is about 544.0477167180.

The spelling of 161031551 in words is "one hundred sixty-one million, thirty-one thousand, five hundred fifty-one".