1221139992 has 32 divisors (see below), whose sum is σ = 3104596800. Its totient is φ = 400147104.

The previous prime is 1221139979. The next prime is 1221139999. The reversal of 1221139992 is 2999311221.

It is a self number, because there is not a number n which added to its sum of digits gives 1221139992.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221139999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 429778 + ... + 432609.

It is an arithmetic number, because the mean of its divisors is an integer number (97018650).

Almost surely, 2^1221139992 is an apocalyptic number.

1221139992 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1221139992 is an abundant number, since it is smaller than the sum of its proper divisors (1883456808).

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

1221139992 is a wasteful number, since it uses less digits than its factorization.

1221139992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862455 (or 862451 counting only the distinct ones).

The product of its digits is 17496, while the sum is 39.

The square root of 1221139992 is about 34944.8135207501. The cubic root of 1221139992 is about 1068.8624449387.

The spelling of 1221139992 in words is "one billion, two hundred twenty-one million, one hundred thirty-nine thousand, nine hundred ninety-two".