1221973872 has 320 divisors, whose sum is σ = 4040884224. Its totient is φ = 310210560.

The previous prime is 1221973867. The next prime is 1221973901. The reversal of 1221973872 is 2783791221.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11863773 + ... + 11863875.

Almost surely, 2^1221973872 is an apocalyptic number.

1221973872 is a gapful number since it is divisible by the number (12) 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 1221973872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2020442112).

1221973872 is an abundant number, since it is smaller than the sum of its proper divisors (2818910352).

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

1221973872 is a wasteful number, since it uses less digits than its factorization.

1221973872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 236 (or 230 counting only the distinct ones).

The product of its digits is 84672, while the sum is 42.

The square root of 1221973872 is about 34956.7428688658. The cubic root of 1221973872 is about 1069.1056876509.

The spelling of 1221973872 in words is "one billion, two hundred twenty-one million, nine hundred seventy-three thousand, eight hundred seventy-two".