161694451723520 has 36 divisors (see below), whose sum is σ = 387308741397060. Its totient is φ = 64677780688896.

The previous prime is 161694451723459. The next prime is 161694451723559. The reversal of 161694451723520 is 25327154496161.

It can be written as a sum of positive squares in 2 ways, for example, as 54075903591424 + 107618548132096 = 7353632^2 + 10373936^2 .

It is a super-2 number, since 2×161694451723520² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63161893925 + ... + 63161896484.

Almost surely, 2^{161694451723520} is an apocalyptic number.

161694451723520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161694451723520 is an abundant number, since it is smaller than the sum of its proper divisors (225614289673540).

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

161694451723520 is an equidigital number, since it uses as much as digits as its factorization.

161694451723520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126323790430 (or 126323790416 counting only the distinct ones).

The product of its (nonzero) digits is 10886400, while the sum is 56.

The spelling of 161694451723520 in words is "one hundred sixty-one trillion, six hundred ninety-four billion, four hundred fifty-one million, seven hundred twenty-three thousand, five hundred twenty".