1221760261 has 4 divisors (see below), whose sum is σ = 1238968224. Its totient is φ = 1204552300.

The previous prime is 1221760231. The next prime is 1221760283. The reversal of 1221760261 is 1620671221.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221760261 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 (1221760231) 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, 8603875 + ... + 8604016.

It is an arithmetic number, because the mean of its divisors is an integer number (309742056).

Almost surely, 2^1221760261 is an apocalyptic number.

It is an amenable number.

1221760261 is a deficient number, since it is larger than the sum of its proper divisors (17207963).

1221760261 is an equidigital number, since it uses as much as digits as its factorization.

1221760261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17207962.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 1221760261 is about 34953.6873734374. The cubic root of 1221760261 is about 1069.0433878891.

The spelling of 1221760261 in words is "one billion, two hundred twenty-one million, seven hundred sixty thousand, two hundred sixty-one".