1221517279 has 2 divisors, whose sum is σ = 1221517280. Its totient is φ = 1221517278.

The previous prime is 1221517261. The next prime is 1221517291. The reversal of 1221517279 is 9727151221.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221517279 - 2⁵ = 1221517247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221517259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610758639 + 610758640.

It is an arithmetic number, because the mean of its divisors is an integer number (610758640).

Almost surely, 2^1221517279 is an apocalyptic number.

1221517279 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221517279 is an equidigital number, since it uses as much as digits as its factorization.

1221517279 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 37.

The square root of 1221517279 is about 34950.2114299756. The cubic root of 1221517279 is about 1068.9725132310.

The spelling of 1221517279 in words is "one billion, two hundred twenty-one million, five hundred seventeen thousand, two hundred seventy-nine".