221091631 has 2 divisors, whose sum is σ = 221091632. Its totient is φ = 221091630.

The previous prime is 221091599. The next prime is 221091653. The reversal of 221091631 is 136190122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221091631 - 2⁵ = 221091599 is a prime.

It is a super-2 number, since 2×221091631² = 97763018596480322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 221091596 and 221091605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221011631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110545815 + 110545816.

It is an arithmetic number, because the mean of its divisors is an integer number (110545816).

Almost surely, 2^221091631 is an apocalyptic number.

221091631 is a deficient number, since it is larger than the sum of its proper divisors (1).

221091631 is an equidigital number, since it uses as much as digits as its factorization.

221091631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 221091631 is about 14869.1503119714. The cubic root of 221091631 is about 604.6779070084.

The spelling of 221091631 in words is "two hundred twenty-one million, ninety-one thousand, six hundred thirty-one".