691457388 has 48 divisors (see below), whose sum is σ = 1719696384. Its totient is φ = 215481600.

The previous prime is 691457381. The next prime is 691457401. The reversal of 691457388 is 883754196.

It is a super-2 number, since 2×691457388² = 956226638839565088, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a self number, because there is not a number n which added to its sum of digits gives 691457388.

It is not an unprimeable number, because it can be changed into a prime (691457381) 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, 19581 + ... + 42027.

It is an arithmetic number, because the mean of its divisors is an integer number (35827008).

Almost surely, 2^691457388 is an apocalyptic number.

691457388 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691457388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (859848192).

691457388 is an abundant number, since it is smaller than the sum of its proper divisors (1028238996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

691457388 is a wasteful number, since it uses less digits than its factorization.

691457388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22622 (or 22620 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 51.

The square root of 691457388 is about 26295.5773467707. The cubic root of 691457388 is about 884.2772943756.

The spelling of 691457388 in words is "six hundred ninety-one million, four hundred fifty-seven thousand, three hundred eighty-eight".