691354521 has 80 divisors (see below), whose sum is σ = 1285054848. Its totient is φ = 363916800.

The previous prime is 691354511. The next prime is 691354523. The reversal of 691354521 is 125453196.

691354521 is a `hidden beast` number, since 6 + 91 + 3 + 545 + 21 = 666.

It is not a de Polignac number, because 691354521 - 2²¹ = 689257369 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (691354523) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 195156 + ... + 198666.

Almost surely, 2^691354521 is an apocalyptic number.

It is an amenable number.

691354521 is a deficient number, since it is larger than the sum of its proper divisors (593700327).

691354521 is a wasteful number, since it uses less digits than its factorization.

691354521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3564 (or 3555 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 691354521 is about 26293.6212987105. The cubic root of 691354521 is about 884.2334413654.

The spelling of 691354521 in words is "six hundred ninety-one million, three hundred fifty-four thousand, five hundred twenty-one".