691231901 has 4 divisors (see below), whose sum is σ = 692874204. Its totient is φ = 689589600.

The previous prime is 691231897. The next prime is 691231921. The reversal of 691231901 is 109132196.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 337603876 + 353628025 = 18374^2 + 18805^2 .

It is a cyclic number.

It is not a de Polignac number, because 691231901 - 2² = 691231897 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691231921) 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, 820520 + ... + 821361.

It is an arithmetic number, because the mean of its divisors is an integer number (173218551).

Almost surely, 2^691231901 is an apocalyptic number.

It is an amenable number.

691231901 is a deficient number, since it is larger than the sum of its proper divisors (1642303).

691231901 is a wasteful number, since it uses less digits than its factorization.

691231901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1642302.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 691231901 is about 26291.2894510711. The cubic root of 691231901 is about 884.1811618127.

The spelling of 691231901 in words is "six hundred ninety-one million, two hundred thirty-one thousand, nine hundred one".