220031205921 has 20 divisors (see below), whose sum is σ = 348023216772. Its totient is φ = 138058795008.

The previous prime is 220031205847. The next prime is 220031205923. The reversal of 220031205921 is 129502130022.

It is a happy number.

220031205921 is a `hidden beast` number, since 2 + 20 + 0 + 31 + 20 + 592 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 155365258896 + 64665947025 = 394164^2 + 254295^2 .

It is not a de Polignac number, because 220031205921 - 2²¹ = 220029108769 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (220031205923) 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 19 ways as a sum of consecutive naturals, for example, 79893760 + ... + 79896513.

Almost surely, 2^220031205921 is an apocalyptic number.

It is an amenable number.

220031205921 is a deficient number, since it is larger than the sum of its proper divisors (127992010851).

220031205921 is a wasteful number, since it uses less digits than its factorization.

220031205921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159790302 (or 159790293 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

Adding to 220031205921 its reverse (129502130022), we get a palindrome (349533335943).

The spelling of 220031205921 in words is "two hundred twenty billion, thirty-one million, two hundred five thousand, nine hundred twenty-one".