161811971 has 8 divisors (see below), whose sum is σ = 167217024. Its totient is φ = 156418560.

The previous prime is 161811959. The next prime is 161811977. The reversal of 161811971 is 179118161.

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

It is not a de Polignac number, because 161811971 - 2²² = 157617667 is a prime.

It is a super-2 number, since 2×161811971² = 52366227917809682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161811977) 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 7 ways as a sum of consecutive naturals, for example, 32291 + ... + 36963.

It is an arithmetic number, because the mean of its divisors is an integer number (20902128).

Almost surely, 2^161811971 is an apocalyptic number.

161811971 is a deficient number, since it is larger than the sum of its proper divisors (5405053).

161811971 is a wasteful number, since it uses less digits than its factorization.

161811971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5821.

The product of its digits is 3024, while the sum is 35.

The square root of 161811971 is about 12720.5334400724. The cubic root of 161811971 is about 544.9251879467.

The spelling of 161811971 in words is "one hundred sixty-one million, eight hundred eleven thousand, nine hundred seventy-one".