161621658 has 24 divisors (see below), whose sum is σ = 382015296. Its totient is φ = 48976200.

The previous prime is 161621651. The next prime is 161621659. The reversal of 161621658 is 856126161.

It is a super-2 number, since 2×161621658² = 52243120669337928, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (161621651) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 407938 + ... + 408333.

It is an arithmetic number, because the mean of its divisors is an integer number (15917304).

Almost surely, 2^161621658 is an apocalyptic number.

161621658 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

161621658 is an abundant number, since it is smaller than the sum of its proper divisors (220393638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161621658 is a wasteful number, since it uses less digits than its factorization.

161621658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816290 (or 816287 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 161621658 is about 12713.0506960367. The cubic root of 161621658 is about 544.7114686302.

The spelling of 161621658 in words is "one hundred sixty-one million, six hundred twenty-one thousand, six hundred fifty-eight".