161639889 has 4 divisors (see below), whose sum is σ = 215519856. Its totient is φ = 107759924.

The previous prime is 161639873. The next prime is 161639899. The reversal of 161639889 is 988936161.

161639889 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161639889 - 2⁴ = 161639873 is a prime.

It is a super-2 number, since 2×161639889² = 52254907431864642, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161639869) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26939979 + ... + 26939984.

It is an arithmetic number, because the mean of its divisors is an integer number (53879964).

Almost surely, 2^161639889 is an apocalyptic number.

It is an amenable number.

161639889 is a deficient number, since it is larger than the sum of its proper divisors (53879967).

161639889 is an equidigital number, since it uses as much as digits as its factorization.

161639889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53879966.

The product of its digits is 559872, while the sum is 51.

The square root of 161639889 is about 12713.7676949046. The cubic root of 161639889 is about 544.7319490979.

The spelling of 161639889 in words is "one hundred sixty-one million, six hundred thirty-nine thousand, eight hundred eighty-nine".