1221556400 has 30 divisors (see below), whose sum is σ = 2934790212. Its totient is φ = 488622400.

The previous prime is 1221556397. The next prime is 1221556409. The reversal of 1221556400 is 46551221.

It is a self number, because there is not a number n which added to its sum of digits gives 1221556400.

It is not an unprimeable number, because it can be changed into a prime (1221556409) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1526546 + ... + 1527345.

Almost surely, 2^1221556400 is an apocalyptic number.

1221556400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221556400 is an abundant number, since it is smaller than the sum of its proper divisors (1713233812).

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

1221556400 is a wasteful number, since it uses less digits than its factorization.

1221556400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3053909 (or 3053898 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 1221556400 is about 34950.7710930675. The cubic root of 1221556400 is about 1068.9839249476.

The spelling of 1221556400 in words is "one billion, two hundred twenty-one million, five hundred fifty-six thousand, four hundred".