691920864 has 72 divisors (see below), whose sum is σ = 1994664672. Its totient is φ = 227473920.

The previous prime is 691920863. The next prime is 691920871. The reversal of 691920864 is 468029196.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691920863) 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, 4569 + ... + 37479.

It is an arithmetic number, because the mean of its divisors is an integer number (27703676).

Almost surely, 2^691920864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691920864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (997332336).

691920864 is an abundant number, since it is smaller than the sum of its proper divisors (1302743808).

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

691920864 is a wasteful number, since it uses less digits than its factorization.

691920864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33000 (or 32989 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 691920864 is about 26304.3886832597. The cubic root of 691920864 is about 884.4748239095.

The spelling of 691920864 in words is "six hundred ninety-one million, nine hundred twenty thousand, eight hundred sixty-four".