221611631 has 2 divisors, whose sum is σ = 221611632. Its totient is φ = 221611630.

The previous prime is 221611619. The next prime is 221611633. The reversal of 221611631 is 136116122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221611631 - 2⁶ = 221611567 is a prime.

It is a super-2 number, since 2×221611631² = 98223429988960322, which contains 22 as substring.

Together with 221611633, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 221611597 and 221611606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221611633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110805815 + 110805816.

It is an arithmetic number, because the mean of its divisors is an integer number (110805816).

Almost surely, 2^221611631 is an apocalyptic number.

221611631 is a deficient number, since it is larger than the sum of its proper divisors (1).

221611631 is an equidigital number, since it uses as much as digits as its factorization.

221611631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 23.

The square root of 221611631 is about 14886.6259105279. The cubic root of 221611631 is about 605.1515964621.

Adding to 221611631 its reverse (136116122), we get a palindrome (357727753).

The spelling of 221611631 in words is "two hundred twenty-one million, six hundred eleven thousand, six hundred thirty-one".