220137721 has 2 divisors, whose sum is σ = 220137722. Its totient is φ = 220137720.

The previous prime is 220137713. The next prime is 220137737. The reversal of 220137721 is 127731022.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 213481321 + 6656400 = 14611^2 + 2580^2 .

It is a cyclic number.

It is not a de Polignac number, because 220137721 - 2³ = 220137713 is a prime.

It is not a weakly prime, because it can be changed into another prime (220137821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110068860 + 110068861.

It is an arithmetic number, because the mean of its divisors is an integer number (110068861).

Almost surely, 2^220137721 is an apocalyptic number.

It is an amenable number.

220137721 is a deficient number, since it is larger than the sum of its proper divisors (1).

220137721 is an equidigital number, since it uses as much as digits as its factorization.

220137721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 220137721 is about 14837.0388218135. The cubic root of 220137721 is about 603.8070164352.

Adding to 220137721 its reverse (127731022), we get a palindrome (347868743).

The spelling of 220137721 in words is "two hundred twenty million, one hundred thirty-seven thousand, seven hundred twenty-one".