161531651 has 4 divisors (see below), whose sum is σ = 164579472. Its totient is φ = 158483832.

The previous prime is 161531647. The next prime is 161531663. The reversal of 161531651 is 156135161.

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 161531651 - 2² = 161531647 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161531551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1523831 + ... + 1523936.

It is an arithmetic number, because the mean of its divisors is an integer number (41144868).

Almost surely, 2^161531651 is an apocalyptic number.

161531651 is a deficient number, since it is larger than the sum of its proper divisors (3047821).

161531651 is an equidigital number, since it uses as much as digits as its factorization.

161531651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3047820.

The product of its digits is 2700, while the sum is 29.

The square root of 161531651 is about 12709.5102580705. The cubic root of 161531651 is about 544.6103333621.

The spelling of 161531651 in words is "one hundred sixty-one million, five hundred thirty-one thousand, six hundred fifty-one".