221521919 has 2 divisors, whose sum is σ = 221521920. Its totient is φ = 221521918.

The previous prime is 221521913. The next prime is 221521943. The reversal of 221521919 is 919125122.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221521919 is a prime.

It is a super-2 number, since 2×221521919² = 98143921194885122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221521913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110760959 + 110760960.

It is an arithmetic number, because the mean of its divisors is an integer number (110760960).

Almost surely, 2^221521919 is an apocalyptic number.

221521919 is a deficient number, since it is larger than the sum of its proper divisors (1).

221521919 is an equidigital number, since it uses as much as digits as its factorization.

221521919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 32.

The square root of 221521919 is about 14883.6124311271. The cubic root of 221521919 is about 605.0699270311.

The spelling of 221521919 in words is "two hundred twenty-one million, five hundred twenty-one thousand, nine hundred nineteen".