1221978624 has 80 divisors (see below), whose sum is σ = 3279754368. Its totient is φ = 404283392.

The previous prime is 1221978599. The next prime is 1221978631. The reversal of 1221978624 is 4268791221.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 207529 + ... + 213335.

Almost surely, 2^1221978624 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221978624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1639877184).

1221978624 is an abundant number, since it is smaller than the sum of its proper divisors (2057775744).

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

1221978624 is an equidigital number, since it uses as much as digits as its factorization.

1221978624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5965 (or 5949 counting only the distinct ones).

The product of its digits is 96768, while the sum is 42.

The square root of 1221978624 is about 34956.8108385190. The cubic root of 1221978624 is about 1069.1070734917.

The spelling of 1221978624 in words is "one billion, two hundred twenty-one million, nine hundred seventy-eight thousand, six hundred twenty-four".