400991631121 has 9 divisors (see below), whose sum is σ = 402057663483. Its totient is φ = 399928422840.

The previous prime is 400991631113. The next prime is 400991631127. The reversal of 400991631121 is 121136199004.

The square root of 400991631121 is 633239.

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., 6482021121 + 394509610000 = 80511^2 + 628100^2 .

It is not a de Polignac number, because 400991631121 - 2³ = 400991631113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400991631127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 361578915 + ... + 361580023.

Almost surely, 2^400991631121 is an apocalyptic number.

400991631121 is the 633239-th square number.

400991631121 is the 316620-th centered octagonal number.

It is an amenable number.

400991631121 is a deficient number, since it is larger than the sum of its proper divisors (1066032362).

400991631121 is an frugal number, since it uses more digits than its factorization.

400991631121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3360 (or 1680 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 37.

The spelling of 400991631121 in words is "four hundred billion, nine hundred ninety-one million, six hundred thirty-one thousand, one hundred twenty-one".