691791388 has 12 divisors (see below), whose sum is σ = 1225221480. Its totient is φ = 341728112.

The previous prime is 691791383. The next prime is 691791403. The reversal of 691791388 is 883197196.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691791383) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1041523 + ... + 1042186.

It is an arithmetic number, because the mean of its divisors is an integer number (102101790).

Almost surely, 2^691791388 is an apocalyptic number.

It is an amenable number.

691791388 is a deficient number, since it is larger than the sum of its proper divisors (533430092).

691791388 is a wasteful number, since it uses less digits than its factorization.

691791388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2083796 (or 2083794 counting only the distinct ones).

The product of its digits is 653184, while the sum is 52.

The square root of 691791388 is about 26301.9274578879. The cubic root of 691791388 is about 884.4196512194.

The spelling of 691791388 in words is "six hundred ninety-one million, seven hundred ninety-one thousand, three hundred eighty-eight".