221020291 has 4 divisors (see below), whose sum is σ = 221050584. Its totient is φ = 220990000.

The previous prime is 221020279. The next prime is 221020321. The reversal of 221020291 is 192020122.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 221020291 - 2¹⁵ = 220987523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221020211) 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, 3231 + ... + 21271.

It is an arithmetic number, because the mean of its divisors is an integer number (55262646).

Almost surely, 2^221020291 is an apocalyptic number.

221020291 is a deficient number, since it is larger than the sum of its proper divisors (30293).

221020291 is a wasteful number, since it uses less digits than its factorization.

221020291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30292.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 221020291 is about 14866.7511918374. The cubic root of 221020291 is about 604.6128625405.

The spelling of 221020291 in words is "two hundred twenty-one million, twenty thousand, two hundred ninety-one".