1221001992 has 96 divisors (see below), whose sum is σ = 3945448800. Its totient is φ = 348854688.

The previous prime is 1221001987. The next prime is 1221002009. The reversal of 1221001992 is 2991001221.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 47098 + ... + 68265.

It is an arithmetic number, because the mean of its divisors is an integer number (41098425).

Almost surely, 2^1221001992 is an apocalyptic number.

1221001992 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1221001992 is an abundant number, since it is smaller than the sum of its proper divisors (2724446808).

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

1221001992 is a wasteful number, since it uses less digits than its factorization.

1221001992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115392 (or 115375 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 1221001992 is about 34942.8389230183. The cubic root of 1221001992 is about 1068.8221796742.

The spelling of 1221001992 in words is "one billion, two hundred twenty-one million, one thousand, nine hundred ninety-two".