9971021025 has 135 divisors (see below), whose sum is σ = 21553242249. Its totient is φ = 4543801920.

The previous prime is 9971020993. The next prime is 9971021041. The reversal of 9971021025 is 5201201799.

The square root of 9971021025 is 99855.

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

It can be written as a sum of positive squares in 4 ways, for example, as 4024760481 + 5946260544 = 63441^2 + 77112^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is not a de Polignac number, because 9971021025 - 2⁵ = 9971020993 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 31454167 + ... + 31454483.

Almost surely, 2^9971021025 is an apocalyptic number.

9971021025 is the 99855-th square number.

9971021025 is the 49928-th centered octagonal number.

It is an amenable number.

9971021025 is an abundant number, since it is smaller than the sum of its proper divisors (11582221224).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9971021025 is an equidigital number, since it uses as much as digits as its factorization.

9971021025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 670 (or 332 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 36.

The cubic root of 9971021025 is about 2152.3515662070.

Multiplying 9971021025 by its sum of digits (36), we get a square (358956756900 = 599130²).

The spelling of 9971021025 in words is "nine billion, nine hundred seventy-one million, twenty-one thousand, twenty-five".