1221321029985 has 48 divisors (see below), whose sum is σ = 2427988867200. Its totient is φ = 556331247360.

The previous prime is 1221321029983. The next prime is 1221321029987. The reversal of 1221321029985 is 5899201231221.

1221321029985 is a `hidden beast` number, since 1 + 221 + 321 + 0 + 29 + 9 + 85 = 666.

It is an interprime number because it is at equal distance from previous prime (1221321029983) and next prime (1221321029987).

It is not a de Polignac number, because 1221321029985 - 2¹ = 1221321029983 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1221321029985.

It is not an unprimeable number, because it can be changed into a prime (1221321029983) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 6810435 + ... + 6987464.

It is an arithmetic number, because the mean of its divisors is an integer number (50583101400).

Almost surely, 2^{1221321029985} is an apocalyptic number.

1221321029985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221321029985 is a deficient number, since it is larger than the sum of its proper divisors (1206667837215).

1221321029985 is a wasteful number, since it uses less digits than its factorization.

1221321029985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13798198 (or 13798195 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 1221321029985 in words is "one trillion, two hundred twenty-one billion, three hundred twenty-one million, twenty-nine thousand, nine hundred eighty-five".