1221660028 has 12 divisors (see below), whose sum is σ = 2206869952. Its totient is φ = 591125760.

The previous prime is 1221660023. The next prime is 1221660053. The reversal of 1221660028 is 8200661221.

It is a junction number, because it is equal to n+sod(n) for n = 1221659978 and 1221660005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221660023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4925925 + ... + 4926172.

Almost surely, 2^1221660028 is an apocalyptic number.

It is an amenable number.

1221660028 is a deficient number, since it is larger than the sum of its proper divisors (985209924).

1221660028 is a wasteful number, since it uses less digits than its factorization.

1221660028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9852132 (or 9852130 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 1221660028 is about 34952.2535468030. The cubic root of 1221660028 is about 1069.0141523782.

The spelling of 1221660028 in words is "one billion, two hundred twenty-one million, six hundred sixty thousand, twenty-eight".