8725731921 has 6 divisors (see below), whose sum is σ = 12603835010. Its totient is φ = 5817154608.

The previous prime is 8725731907. The next prime is 8725731947. The reversal of 8725731921 is 1291375278.

8725731921 is a `hidden beast` number, since 8 + 72 + 573 + 1 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7475331600 + 1250400321 = 86460^2 + 35361^2 .

It is not a de Polignac number, because 8725731921 - 2¹⁵ = 8725699153 is a prime.

It is a super-2 number, since 2×8725731921² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8725731991) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 484762876 + ... + 484762893.

Almost surely, 2^8725731921 is an apocalyptic number.

It is an amenable number.

8725731921 is a deficient number, since it is larger than the sum of its proper divisors (3878103089).

8725731921 is a wasteful number, since it uses less digits than its factorization.

8725731921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 969525775 (or 969525772 counting only the distinct ones).

The product of its digits is 211680, while the sum is 45.

The square root of 8725731921 is about 93411.6262624733. The cubic root of 8725731921 is about 2058.7358254416.

The spelling of 8725731921 in words is "eight billion, seven hundred twenty-five million, seven hundred thirty-one thousand, nine hundred twenty-one".