221618923 has 2 divisors, whose sum is σ = 221618924. Its totient is φ = 221618922.

The previous prime is 221618921. The next prime is 221618933. The reversal of 221618923 is 329816122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221618923 - 2¹ = 221618921 is a prime.

It is a super-2 number, since 2×221618923² = 98229894063359858, which contains 22 as substring.

Together with 221618921, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (221618921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110809461 + 110809462.

It is an arithmetic number, because the mean of its divisors is an integer number (110809462).

Almost surely, 2^221618923 is an apocalyptic number.

221618923 is a deficient number, since it is larger than the sum of its proper divisors (1).

221618923 is an equidigital number, since it uses as much as digits as its factorization.

221618923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 34.

The square root of 221618923 is about 14886.8708263355. The cubic root of 221618923 is about 605.1582337747.

The spelling of 221618923 in words is "two hundred twenty-one million, six hundred eighteen thousand, nine hundred twenty-three".