1221221992 has 8 divisors (see below), whose sum is σ = 2289791250. Its totient is φ = 610610992.

The previous prime is 1221221983. The next prime is 1221221993. The reversal of 1221221992 is 2991221221.

It can be written as a sum of positive squares in only one way, i.e., 618715876 + 602506116 = 24874^2 + 24546^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (1221221993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 76326367 + ... + 76326382.

Almost surely, 2^1221221992 is an apocalyptic number.

It is an amenable number.

1221221992 is a deficient number, since it is larger than the sum of its proper divisors (1068569258).

1221221992 is a wasteful number, since it uses less digits than its factorization.

1221221992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152652755 (or 152652751 counting only the distinct ones).

The product of its digits is 2592, while the sum is 31.

The square root of 1221221992 is about 34945.9867796003. The cubic root of 1221221992 is about 1068.8863692387.

The spelling of 1221221992 in words is "one billion, two hundred twenty-one million, two hundred twenty-one thousand, nine hundred ninety-two".