16401212125281 has 9 divisors (see below), whose sum is σ = 23690657285841. Its totient is φ = 10934133317172.

The previous prime is 16401212125261. The next prime is 16401212125289. The reversal of 16401212125281 is 18252121210461.

The square root of 16401212125281 is 4049841.

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

16401212125281 is a `hidden beast` number, since 1 + 6 + 4 + 0 + 1 + 2 + 121 + 2 + 528 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 16401212125281 - 2²⁷ = 16401077907553 is a prime.

It is a super-2 number, since 2×16401212125281² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16401212125289) 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, 11474550 + ... + 12824496.

Almost surely, 2^{16401212125281} is an apocalyptic number.

16401212125281 is the 4049841-st square number.

16401212125281 is the 2024921-st centered octagonal number.

It is an amenable number.

16401212125281 is a deficient number, since it is larger than the sum of its proper divisors (7289445160560).

16401212125281 is an frugal number, since it uses more digits than its factorization.

16401212125281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2699900 (or 1349950 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

Multiplying 16401212125281 by its sum of digits (36), we get a square (590443636510116 = 24299046²).

The spelling of 16401212125281 in words is "sixteen trillion, four hundred one billion, two hundred twelve million, one hundred twenty-five thousand, two hundred eighty-one".