221020981 has 4 divisors (see below), whose sum is σ = 222611200. Its totient is φ = 219430764.

The previous prime is 221020957. The next prime is 221021033. The reversal of 221020981 is 189020122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 189020122 = 2 ⋅94510061.

It is a cyclic number.

It is not a de Polignac number, because 221020981 - 2⁹ = 221020469 is a prime.

It is a super-2 number, since 2×221020981² = 97700548084404722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221020781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 794901 + ... + 795178.

It is an arithmetic number, because the mean of its divisors is an integer number (55652800).

Almost surely, 2^221020981 is an apocalyptic number.

It is an amenable number.

221020981 is a deficient number, since it is larger than the sum of its proper divisors (1590219).

221020981 is a wasteful number, since it uses less digits than its factorization.

221020981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1590218.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 221020981 is about 14866.7743979654. The cubic root of 221020981 is about 604.6134917172.

The spelling of 221020981 in words is "two hundred twenty-one million, twenty thousand, nine hundred eighty-one".