221091649 has 4 divisors (see below), whose sum is σ = 221299540. Its totient is φ = 220883760.

The previous prime is 221091631. The next prime is 221091653. The reversal of 221091649 is 946190122.

221091649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 100641024 + 120450625 = 10032^2 + 10975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221091649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221091449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102342 + ... + 104479.

It is an arithmetic number, because the mean of its divisors is an integer number (55324885).

Almost surely, 2^221091649 is an apocalyptic number.

It is an amenable number.

221091649 is a deficient number, since it is larger than the sum of its proper divisors (207891).

221091649 is a wasteful number, since it uses less digits than its factorization.

221091649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207890.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 221091649 is about 14869.1509172515. The cubic root of 221091649 is about 604.6779234182.

The spelling of 221091649 in words is "two hundred twenty-one million, ninety-one thousand, six hundred forty-nine".