691451091 has 12 divisors (see below), whose sum is σ = 1017607968. Its totient is φ = 452269584.

The previous prime is 691451083. The next prime is 691451099. The reversal of 691451091 is 190154196.

It is an interprime number because it is at equal distance from previous prime (691451083) and next prime (691451099).

It is not a de Polignac number, because 691451091 - 2³ = 691451083 is a prime.

It is a super-2 number, since 2×691451091² = 956209222490180562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (691451099) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 724315 + ... + 725268.

It is an arithmetic number, because the mean of its divisors is an integer number (84800664).

Almost surely, 2^691451091 is an apocalyptic number.

691451091 is a deficient number, since it is larger than the sum of its proper divisors (326156877).

691451091 is a wasteful number, since it uses less digits than its factorization.

691451091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449642 (or 1449639 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 691451091 is about 26295.4576115344. The cubic root of 691451091 is about 884.2746100400.

The spelling of 691451091 in words is "six hundred ninety-one million, four hundred fifty-one thousand, ninety-one".