1221320265 has 64 divisors (see below), whose sum is σ = 2167603200. Its totient is φ = 582301440.

The previous prime is 1221320251. The next prime is 1221320281. The reversal of 1221320265 is 5620231221.

1221320265 is digitally balanced in base 4 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 1221320265 - 2¹⁰ = 1221319241 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3499311 + ... + 3499659.

It is an arithmetic number, because the mean of its divisors is an integer number (33868800).

Almost surely, 2^1221320265 is an apocalyptic number.

1221320265 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221320265 is a deficient number, since it is larger than the sum of its proper divisors (946282935).

1221320265 is a wasteful number, since it uses less digits than its factorization.

1221320265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 1221320265 is about 34947.3928212106. The cubic root of 1221320265 is about 1068.9150399345.

Adding to 1221320265 its reverse (5620231221), we get a palindrome (6841551486).

The spelling of 1221320265 in words is "one billion, two hundred twenty-one million, three hundred twenty thousand, two hundred sixty-five".