213631 has 4 divisors (see below), whose sum is σ = 233064. Its totient is φ = 194200.

The previous prime is 213623. The next prime is 213637. The reversal of 213631 is 136312.

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

It is a cyclic number.

It is not a de Polignac number, because 213631 - 2³ = 213623 is a prime.

It is a super-2 number, since 2×213631² = 91276408322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9700 + ... + 9721.

It is an arithmetic number, because the mean of its divisors is an integer number (58266).

2²¹³⁶³¹ is an apocalyptic number.

213631 is a deficient number, since it is larger than the sum of its proper divisors (19433).

213631 is a wasteful number, since it uses less digits than its factorization.

213631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19432.

The product of its digits is 108, while the sum is 16.

The square root of 213631 is about 462.2023366449. The cubic root of 213631 is about 59.7798413054.

Adding to 213631 its reverse (136312), we get a palindrome (349943).

The spelling of 213631 in words is "two hundred thirteen thousand, six hundred thirty-one".