23131221 has 8 divisors (see below), whose sum is σ = 30879264. Its totient is φ = 15402000.

The previous prime is 23131211. The next prime is 23131231. The reversal of 23131221 is 12213132.

It is an interprime number because it is at equal distance from previous prime (23131211) and next prime (23131231).

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

It is not a de Polignac number, because 23131221 - 2¹³ = 23123029 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 23131221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23131211) 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, 1530 + ... + 6971.

It is an arithmetic number, because the mean of its divisors is an integer number (3859908).

Almost surely, 2^23131221 is an apocalyptic number.

It is an amenable number.

23131221 is a deficient number, since it is larger than the sum of its proper divisors (7748043).

23131221 is an equidigital number, since it uses as much as digits as its factorization.

23131221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9411.

The product of its digits is 72, while the sum is 15.

The square root of 23131221 is about 4809.4928007015. The cubic root of 23131221 is about 284.9265061342.

Adding to 23131221 its reverse (12213132), we get a palindrome (35344353).

The spelling of 23131221 in words is "twenty-three million, one hundred thirty-one thousand, two hundred twenty-one".