1221378768 has 60 divisors (see below), whose sum is σ = 3465018180. Its totient is φ = 401545728.

The previous prime is 1221378749. The next prime is 1221378791. The reversal of 1221378768 is 8678731221.

It can be written as a sum of positive squares in 2 ways, for example, as 413227584 + 808151184 = 20328^2 + 28428^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47583 + ... + 68606.

It is an arithmetic number, because the mean of its divisors is an integer number (57750303).

Almost surely, 2^1221378768 is an apocalyptic number.

1221378768 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1221378768 is an abundant number, since it is smaller than the sum of its proper divisors (2243639412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221378768 is a wasteful number, since it uses less digits than its factorization.

1221378768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116276 (or 116267 counting only the distinct ones).

The product of its digits is 225792, while the sum is 45.

The square root of 1221378768 is about 34948.2298264161. The cubic root of 1221378768 is about 1068.9321071854.

The spelling of 1221378768 in words is "one billion, two hundred twenty-one million, three hundred seventy-eight thousand, seven hundred sixty-eight".