16623551685601 has 9 divisors (see below), whose sum is σ = 19337634140499. Its totient is φ = 14248734124464.

The previous prime is 16623551685571. The next prime is 16623551685607. The reversal of 16623551685601 is 10658615532661.

The square root of 16623551685601 is 4077199.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 6799238776225 + 9824312909376 = 2607535^2 + 3134376^2 .

It is not a de Polignac number, because 16623551685601 - 2⁵ = 16623551685569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16623551685607) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 28249165 + ... + 28831621.

It is an arithmetic number, because the mean of its divisors is an integer number (2148626015611).

Almost surely, 2^{16623551685601} is an apocalyptic number.

16623551685601 is the 4077199-th square number.

16623551685601 is the 2038600-th centered octagonal number.

It is an amenable number.

16623551685601 is a deficient number, since it is larger than the sum of its proper divisors (2714082454898).

16623551685601 is an frugal number, since it uses more digits than its factorization.

16623551685601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1164928 (or 582464 counting only the distinct ones).

The product of its (nonzero) digits is 7776000, while the sum is 55.

It can be divided in two parts, 166235 and 51685601, that added together give a triangular number (51851836 = T₁₀₁₈₃).

The spelling of 16623551685601 in words is "sixteen trillion, six hundred twenty-three billion, five hundred fifty-one million, six hundred eighty-five thousand, six hundred one".