220001981 has 4 divisors (see below), whose sum is σ = 232943292. Its totient is φ = 207060672.

The previous prime is 220001953. The next prime is 220002031. The reversal of 220001981 is 189100022.

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 126202756 + 93799225 = 11234^2 + 9685^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-220001981 is a prime.

It is a super-2 number, since 2×220001981² = 96801743287848722, 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 (220001921) 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, 6470630 + ... + 6470663.

It is an arithmetic number, because the mean of its divisors is an integer number (58235823).

Almost surely, 2^220001981 is an apocalyptic number.

It is an amenable number.

220001981 is a deficient number, since it is larger than the sum of its proper divisors (12941311).

220001981 is a wasteful number, since it uses less digits than its factorization.

220001981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12941310.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 220001981 is about 14832.4637535374. The cubic root of 220001981 is about 603.6828856322.

The spelling of 220001981 in words is "two hundred twenty million, one thousand, nine hundred eighty-one".