1221121011999 has 32 divisors (see below), whose sum is σ = 1949041188864. Its totient is φ = 664907142240.

The previous prime is 1221121011977. The next prime is 1221121012021. The reversal of 1221121011999 is 9991101211221.

It is an interprime number because it is at equal distance from previous prime (1221121011977) and next prime (1221121012021).

It is not a de Polignac number, because 1221121011999 - 2¹² = 1221121007903 is a prime.

It is a super-2 number, since 2×1221121011999² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221121011919) 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, 4679437 + ... + 4933494.

It is an arithmetic number, because the mean of its divisors is an integer number (60907537152).

Almost surely, 2^{1221121011999} is an apocalyptic number.

1221121011999 is a deficient number, since it is larger than the sum of its proper divisors (727920176865).

1221121011999 is a wasteful number, since it uses less digits than its factorization.

1221121011999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9613227.

The product of its (nonzero) digits is 5832, while the sum is 39.

The spelling of 1221121011999 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-one million, eleven thousand, nine hundred ninety-nine".