161651661 has 8 divisors (see below), whose sum is σ = 216099840. Its totient is φ = 107485632.

The previous prime is 161651627. The next prime is 161651669. The reversal of 161651661 is 166156161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 161651661 - 2⁷ = 161651533 is a prime.

It is a super-2 number, since 2×161651661² = 52262519008117842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161651669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 69196 + ... + 71493.

It is an arithmetic number, because the mean of its divisors is an integer number (27012480).

Almost surely, 2^161651661 is an apocalyptic number.

It is an amenable number.

161651661 is a deficient number, since it is larger than the sum of its proper divisors (54448179).

161651661 is a wasteful number, since it uses less digits than its factorization.

161651661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141075.

The product of its digits is 6480, while the sum is 33.

The square root of 161651661 is about 12714.2306491584. The cubic root of 161651661 is about 544.7451727910.

The spelling of 161651661 in words is "one hundred sixty-one million, six hundred fifty-one thousand, six hundred sixty-one".