231890221 has 4 divisors (see below), whose sum is σ = 232885692. Its totient is φ = 230894752.

The previous prime is 231890179. The next prime is 231890233. The reversal of 231890221 is 122098132.

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 56460196 + 175430025 = 7514^2 + 13245^2 .

It is a cyclic number.

It is not a de Polignac number, because 231890221 - 2⁹ = 231889709 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 231890221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231890921) 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, 497386 + ... + 497851.

It is an arithmetic number, because the mean of its divisors is an integer number (58221423).

Almost surely, 2^231890221 is an apocalyptic number.

It is an amenable number.

231890221 is a deficient number, since it is larger than the sum of its proper divisors (995471).

231890221 is an equidigital number, since it uses as much as digits as its factorization.

231890221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 995470.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 231890221 is about 15227.9421131025. The cubic root of 231890221 is about 614.3664314933.

The spelling of 231890221 in words is "two hundred thirty-one million, eight hundred ninety thousand, two hundred twenty-one".