213431021 has 8 divisors (see below), whose sum is σ = 214684344. Its totient is φ = 212181760.

The previous prime is 213431017. The next prime is 213431051. The reversal of 213431021 is 120134312.

It can be written as a sum of positive squares in 4 ways, for example, as 37576900 + 175854121 = 6130^2 + 13261^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 213431021 - 2² = 213431017 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 (213431051) 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, 223481 + ... + 224433.

It is an arithmetic number, because the mean of its divisors is an integer number (26835543).

Almost surely, 2^213431021 is an apocalyptic number.

It is an amenable number.

213431021 is a deficient number, since it is larger than the sum of its proper divisors (1253323).

213431021 is an equidigital number, since it uses as much as digits as its factorization.

213431021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2031.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 213431021 is about 14609.2785927300. The cubic root of 213431021 is about 597.6118227012.

Adding to 213431021 its reverse (120134312), we get a palindrome (333565333).

The spelling of 213431021 in words is "two hundred thirteen million, four hundred thirty-one thousand, twenty-one".