8457691220521 has 9 divisors (see below), whose sum is σ = 8486226274071. Its totient is φ = 8429251825152.

The previous prime is 8457691220501. The next prime is 8457691220533. The reversal of 8457691220521 is 1250221967548.

It is a happy number.

The square root of 8457691220521 is 2908211.

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., 8230673277225 + 227017943296 = 2868915^2 + 476464^2 .

It is not a de Polignac number, because 8457691220521 - 2²⁷ = 8457557002793 is a prime.

It is a super-2 number, since 2×8457691220521² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8457691220501) 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, 892816041 + ... + 892825513.

Almost surely, 2^{8457691220521} is an apocalyptic number.

8457691220521 is the 2908211-st square number.

8457691220521 is the 1454106-th centered octagonal number.

It is an amenable number.

8457691220521 is a deficient number, since it is larger than the sum of its proper divisors (28535053550).

8457691220521 is an frugal number, since it uses more digits than its factorization.

8457691220521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19560 (or 9780 counting only the distinct ones).

The product of its (nonzero) digits is 2419200, while the sum is 52.

The spelling of 8457691220521 in words is "eight trillion, four hundred fifty-seven billion, six hundred ninety-one million, two hundred twenty thousand, five hundred twenty-one".