1221887564 has 24 divisors (see below), whose sum is σ = 2181489408. Its totient is φ = 598708880.

The previous prime is 1221887551. The next prime is 1221887603. The reversal of 1221887564 is 4657881221.

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, 34547 + ... + 60309.

It is an arithmetic number, because the mean of its divisors is an integer number (90895392).

Almost surely, 2^1221887564 is an apocalyptic number.

It is an amenable number.

1221887564 is a deficient number, since it is larger than the sum of its proper divisors (959601844).

1221887564 is a wasteful number, since it uses less digits than its factorization.

1221887564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26005 (or 26003 counting only the distinct ones).

The product of its digits is 215040, while the sum is 44.

The square root of 1221887564 is about 34955.5083499010. The cubic root of 1221887564 is about 1069.0805167510.

The spelling of 1221887564 in words is "one billion, two hundred twenty-one million, eight hundred eighty-seven thousand, five hundred sixty-four".