16161561 has 24 divisors (see below), whose sum is σ = 25683840. Its totient is φ = 9730656.

The previous prime is 16161559. The next prime is 16161569. The reversal of 16161561 is 16516161.

It is not a de Polignac number, because 16161561 - 2¹ = 16161559 is a prime.

It is a super-2 number, since 2×16161561² = 522392107913442, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16161569) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4030 + ... + 6968.

It is an arithmetic number, because the mean of its divisors is an integer number (1070160).

Almost surely, 2^16161561 is an apocalyptic number.

It is an amenable number.

16161561 is a deficient number, since it is larger than the sum of its proper divisors (9522279).

16161561 is a wasteful number, since it uses less digits than its factorization.

16161561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3005 (or 3002 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 16161561 is about 4020.1444003916. The cubic root of 16161561 is about 252.8295132667.

The spelling of 16161561 in words is "sixteen million, one hundred sixty-one thousand, five hundred sixty-one".