691267921 has 8 divisors (see below), whose sum is σ = 733149504. Its totient is φ = 650371920.

The previous prime is 691267919. The next prime is 691267931. The reversal of 691267921 is 129762196.

It is a happy number.

691267921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 691267921 - 2¹ = 691267919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691267901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 244951 + ... + 247756.

It is an arithmetic number, because the mean of its divisors is an integer number (91643688).

Almost surely, 2^691267921 is an apocalyptic number.

691267921 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

691267921 is a deficient number, since it is larger than the sum of its proper divisors (41881583).

691267921 is a wasteful number, since it uses less digits than its factorization.

691267921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492791.

The product of its digits is 81648, while the sum is 43.

The square root of 691267921 is about 26291.9744598994. The cubic root of 691267921 is about 884.1965197325.

The spelling of 691267921 in words is "six hundred ninety-one million, two hundred sixty-seven thousand, nine hundred twenty-one".