691171989 has 16 divisors (see below), whose sum is σ = 942025728. Its totient is φ = 450567792.

The previous prime is 691171969. The next prime is 691171991. The reversal of 691171989 is 989171196.

It is not a de Polignac number, because 691171989 - 2⁹ = 691171477 is a prime.

It is a super-2 number, since 2×691171989² = 955437436756432242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691171969) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 278934 + ... + 281400.

It is an arithmetic number, because the mean of its divisors is an integer number (58876608).

Almost surely, 2^691171989 is an apocalyptic number.

It is an amenable number.

691171989 is a deficient number, since it is larger than the sum of its proper divisors (250853739).

691171989 is a wasteful number, since it uses less digits than its factorization.

691171989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4504.

The product of its digits is 244944, while the sum is 51.

The square root of 691171989 is about 26290.1500376091. The cubic root of 691171989 is about 884.1556158311.

The spelling of 691171989 in words is "six hundred ninety-one million, one hundred seventy-one thousand, nine hundred eighty-nine".