231791821 has 4 divisors (see below), whose sum is σ = 245426652. Its totient is φ = 218156992.

The previous prime is 231791779. The next prime is 231791831. The reversal of 231791821 is 128197132.

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 193488100 + 38303721 = 13910^2 + 6189^2 .

It is a cyclic number.

It is not a de Polignac number, because 231791821 - 2¹¹ = 231789773 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 (231791831) 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, 6817390 + ... + 6817423.

It is an arithmetic number, because the mean of its divisors is an integer number (61356663).

Almost surely, 2^231791821 is an apocalyptic number.

It is an amenable number.

231791821 is a deficient number, since it is larger than the sum of its proper divisors (13634831).

231791821 is a wasteful number, since it uses less digits than its factorization.

231791821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13634830.

The product of its digits is 6048, while the sum is 34.

The square root of 231791821 is about 15224.7108675337. The cubic root of 231791821 is about 614.2795193766.

The spelling of 231791821 in words is "two hundred thirty-one million, seven hundred ninety-one thousand, eight hundred twenty-one".