161617720 has 32 divisors (see below), whose sum is σ = 396699120. Its totient is φ = 58769920.

The previous prime is 161617717. The next prime is 161617727. The reversal of 161617720 is 27716161.

It is a super-2 number, since 2×161617720² = 52240574835996800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161617727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183217 + ... + 184096.

Almost surely, 2^161617720 is an apocalyptic number.

161617720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161617720 is an abundant number, since it is smaller than the sum of its proper divisors (235081400).

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

161617720 is a wasteful number, since it uses less digits than its factorization.

161617720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367335 (or 367331 counting only the distinct ones).

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 161617720 is about 12712.8958148803. The cubic root of 161617720 is about 544.7070445301.

The spelling of 161617720 in words is "one hundred sixty-one million, six hundred seventeen thousand, seven hundred twenty".