1206215991 has 12 divisors (see below), whose sum is σ = 1742645632. Its totient is φ = 803990016.

The previous prime is 1206215971. The next prime is 1206215993. The reversal of 1206215991 is 1995126021.

1206215991 is a `hidden beast` number, since 1 + 2 + 0 + 62 + 1 + 599 + 1 = 666.

It is not a de Polignac number, because 1206215991 - 2¹⁹ = 1205691703 is a prime.

It is a super-2 number, since 2×1206215991² = 2909914033888224162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1206215993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56490 + ... + 74856.

Almost surely, 2^1206215991 is an apocalyptic number.

1206215991 is a deficient number, since it is larger than the sum of its proper divisors (536429641).

1206215991 is a wasteful number, since it uses less digits than its factorization.

1206215991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25670 (or 25667 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 1206215991 is about 34730.6203658961. The cubic root of 1206215991 is about 1064.4902645639.

The spelling of 1206215991 in words is "one billion, two hundred six million, two hundred fifteen thousand, nine hundred ninety-one".