161642561 has 8 divisors (see below), whose sum is σ = 162786624. Its totient is φ = 160503120.

The previous prime is 161642543. The next prime is 161642573. The reversal of 161642561 is 165246161.

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

It is a cyclic number.

It is not a de Polignac number, because 161642561 - 2¹⁰ = 161641537 is a prime.

It is a super-2 number, since 2×161642561² = 52256635053277442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161641561) 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, 94631 + ... + 96323.

It is an arithmetic number, because the mean of its divisors is an integer number (20348328).

Almost surely, 2^161642561 is an apocalyptic number.

It is an amenable number.

161642561 is a deficient number, since it is larger than the sum of its proper divisors (1144063).

161642561 is a wasteful number, since it uses less digits than its factorization.

161642561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2311.

The product of its digits is 8640, while the sum is 32.

The square root of 161642561 is about 12713.8727774034. The cubic root of 161642561 is about 544.7349506585.

The spelling of 161642561 in words is "one hundred sixty-one million, six hundred forty-two thousand, five hundred sixty-one".