1221222400 has 168 divisors, whose sum is σ = 3108182760. Its totient is φ = 475791360.

The previous prime is 1221222377. The next prime is 1221222413. The reversal of 1221222400 is 42221221.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13721556 + ... + 13721644.

Almost surely, 2^1221222400 is an apocalyptic number.

1221222400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221222400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1554091380).

1221222400 is an abundant number, since it is smaller than the sum of its proper divisors (1886960360).

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

1221222400 is an frugal number, since it uses more digits than its factorization.

1221222400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 1221222400 is about 34945.9926171800. The cubic root of 1221222400 is about 1068.8864882740.

Adding to 1221222400 its reverse (42221221), we get a palindrome (1263443621).

The spelling of 1221222400 in words is "one billion, two hundred twenty-one million, two hundred twenty-two thousand, four hundred".