1221628784 has 40 divisors (see below), whose sum is σ = 2428438320. Its totient is φ = 594982400.

The previous prime is 1221628783. The next prime is 1221628843. The reversal of 1221628784 is 4878261221.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221628783) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 616307 + ... + 618285.

It is an arithmetic number, because the mean of its divisors is an integer number (60710958).

Almost surely, 2^1221628784 is an apocalyptic number.

It is an amenable number.

1221628784 is a deficient number, since it is larger than the sum of its proper divisors (1206809536).

1221628784 is a wasteful number, since it uses less digits than its factorization.

1221628784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2969 (or 2963 counting only the distinct ones).

The product of its digits is 86016, while the sum is 41.

The square root of 1221628784 is about 34951.8065913623. The cubic root of 1221628784 is about 1069.0050389418.

The spelling of 1221628784 in words is "one billion, two hundred twenty-one million, six hundred twenty-eight thousand, seven hundred eighty-four".