1221115959 has 32 divisors (see below), whose sum is σ = 2176320000. Its totient is φ = 661053312.

The previous prime is 1221115949. The next prime is 1221115969. The reversal of 1221115959 is 9595111221.

It is an interprime number because it is at equal distance from previous prime (1221115949) and next prime (1221115969).

It is not a de Polignac number, because 1221115959 - 2⁵ = 1221115927 is a prime.

It is a super-2 number, since 2×1221115959² = 2982248370648979362, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221115949) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 166434 + ... + 173615.

It is an arithmetic number, because the mean of its divisors is an integer number (68010000).

Almost surely, 2^1221115959 is an apocalyptic number.

1221115959 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

1221115959 is a deficient number, since it is larger than the sum of its proper divisors (955204041).

1221115959 is a wasteful number, since it uses less digits than its factorization.

1221115959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340084 (or 340078 counting only the distinct ones).

The product of its digits is 8100, while the sum is 36.

The square root of 1221115959 is about 34944.4696482863. The cubic root of 1221115959 is about 1068.8554328735.

The spelling of 1221115959 in words is "one billion, two hundred twenty-one million, one hundred fifteen thousand, nine hundred fifty-nine".