221951291 has 4 divisors (see below), whose sum is σ = 222247584. Its totient is φ = 221655000.

The previous prime is 221951287. The next prime is 221951329. The reversal of 221951291 is 192159122.

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

It is a cyclic number.

It is not a de Polignac number, because 221951291 - 2² = 221951287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221951591) 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 in 3 ways as a sum of consecutive naturals, for example, 147020 + ... + 148521.

It is an arithmetic number, because the mean of its divisors is an integer number (55561896).

Almost surely, 2^221951291 is an apocalyptic number.

221951291 is a deficient number, since it is larger than the sum of its proper divisors (296293).

221951291 is an equidigital number, since it uses as much as digits as its factorization.

221951291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296292.

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

The square root of 221951291 is about 14898.0297690668. The cubic root of 221951291 is about 605.4606068204.

The spelling of 221951291 in words is "two hundred twenty-one million, nine hundred fifty-one thousand, two hundred ninety-one".