1221120556 has 6 divisors (see below), whose sum is σ = 2136960980. Its totient is φ = 610560276.

The previous prime is 1221120553. The next prime is 1221120587. The reversal of 1221120556 is 6550211221.

It is a super-2 number, since 2×1221120556² = 2982270824571498272, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221120556.

It is not an unprimeable number, because it can be changed into a prime (1221120553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 152640066 + ... + 152640073.

Almost surely, 2^1221120556 is an apocalyptic number.

It is an amenable number.

1221120556 is a deficient number, since it is larger than the sum of its proper divisors (915840424).

1221120556 is a wasteful number, since it uses less digits than its factorization.

1221120556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305280143 (or 305280141 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 1221120556 is about 34944.5354240116. The cubic root of 1221120556 is about 1068.8567741390.

Adding to 1221120556 its reverse (6550211221), we get a palindrome (7771331777).

The spelling of 1221120556 in words is "one billion, two hundred twenty-one million, one hundred twenty thousand, five hundred fifty-six".