961009656721 has 9 divisors (see below), whose sum is σ = 973406762811. Its totient is φ = 948768513264.

The previous prime is 961009656709. The next prime is 961009656743. The reversal of 961009656721 is 127656900169.

The square root of 961009656721 is 980311.

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

961009656721 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 only one way, i.e., 25998015121 + 935011641600 = 161239^2 + 966960^2 .

It is not a de Polignac number, because 961009656721 - 2¹¹ = 961009654673 is a prime.

It is a super-2 number, since 2×961009656721² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (961009656751) 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, 77438365 + ... + 77450773.

It is an arithmetic number, because the mean of its divisors is an integer number (108156306979).

Almost surely, 2^961009656721 is an apocalyptic number.

961009656721 is the 980311-st square number.

961009656721 is the 490156-th centered octagonal number.

It is an amenable number.

961009656721 is a deficient number, since it is larger than the sum of its proper divisors (12397106090).

961009656721 is an frugal number, since it uses more digits than its factorization.

961009656721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24976 (or 12488 counting only the distinct ones).

The product of its (nonzero) digits is 1224720, while the sum is 52.

The spelling of 961009656721 in words is "nine hundred sixty-one billion, nine million, six hundred fifty-six thousand, seven hundred twenty-one".