15531804163681 has 9 divisors (see below), whose sum is σ = 16818517974681. Its totient is φ = 14337002704752.

The previous prime is 15531804163619. The next prime is 15531804163691. The reversal of 15531804163681 is 18636140813551.

The square root of 15531804163681 is 3941041.

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

15531804163681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 286215370081 + 15245588793600 = 534991^2 + 3904560^2 .

It is not a de Polignac number, because 15531804163681 - 2¹³ = 15531804155489 is a prime.

It is a super-2 number, since 2×15531804163681² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15531804163691) 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, 51081955 + ... + 51385111.

It is an arithmetic number, because the mean of its divisors is an integer number (1868724219409).

Almost surely, 2^{15531804163681} is an apocalyptic number.

15531804163681 is the 3941041-st square number.

15531804163681 is the 1970521-st centered octagonal number.

It is an amenable number.

15531804163681 is a deficient number, since it is larger than the sum of its proper divisors (1286713811000).

15531804163681 is an frugal number, since it uses more digits than its factorization.

15531804163681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 606340 (or 303170 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 52.

The spelling of 15531804163681 in words is "fifteen trillion, five hundred thirty-one billion, eight hundred four million, one hundred sixty-three thousand, six hundred eighty-one".