220121765 has 4 divisors (see below), whose sum is σ = 264146124. Its totient is φ = 176097408.

The previous prime is 220121747. The next prime is 220121767. The reversal of 220121765 is 567121022.

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 160554241 + 59567524 = 12671^2 + 7718^2 .

It is a cyclic number.

It is not a de Polignac number, because 220121765 - 2⁸ = 220121509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220121767) 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, 22012172 + ... + 22012181.

It is an arithmetic number, because the mean of its divisors is an integer number (66036531).

Almost surely, 2^220121765 is an apocalyptic number.

It is an amenable number.

220121765 is a deficient number, since it is larger than the sum of its proper divisors (44024359).

220121765 is an equidigital number, since it uses as much as digits as its factorization.

220121765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44024358.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 220121765 is about 14836.5011036969. The cubic root of 220121765 is about 603.7924277231.

Adding to 220121765 its reverse (567121022), we get a palindrome (787242787).

The spelling of 220121765 in words is "two hundred twenty million, one hundred twenty-one thousand, seven hundred sixty-five".