161694720 has 396 divisors, whose sum is σ = 637067340. Its totient is φ = 37847040.

The previous prime is 161694719. The next prime is 161694779. The reversal of 161694720 is 27496161.

It can be written as a sum of positive squares in 2 ways, for example, as 71368704 + 90326016 = 8448^2 + 9504^2 .

It is a tau number, because it is divible by the number of its divisors (396).

It is a super-2 number, since 2×161694720² = 52290364951756800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5575666 + ... + 5575694.

Almost surely, 2^161694720 is an apocalyptic number.

161694720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161694720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (318533670).

161694720 is an abundant number, since it is smaller than the sum of its proper divisors (475372620).

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

161694720 is a wasteful number, since it uses less digits than its factorization.

161694720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 161694720 is about 12715.9238752047. The cubic root of 161694720 is about 544.7935362491.

The spelling of 161694720 in words is "one hundred sixty-one million, six hundred ninety-four thousand, seven hundred twenty".