211221999956 has 24 divisors (see below), whose sum is σ = 403253647776. Its totient is φ = 96007226720.

The previous prime is 211221999929. The next prime is 211221999997. The reversal of 211221999956 is 659999122112.

It is a super-2 number, since 2×211221999956² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2903135 + ... + 2975001.

It is an arithmetic number, because the mean of its divisors is an integer number (16802235324).

Almost surely, 2^211221999956 is an apocalyptic number.

It is an amenable number.

211221999956 is a deficient number, since it is larger than the sum of its proper divisors (192031647820).

211221999956 is a wasteful number, since it uses less digits than its factorization.

211221999956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138679 (or 138677 counting only the distinct ones).

The product of its digits is 1574640, while the sum is 56.

The spelling of 211221999956 in words is "two hundred eleven billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred fifty-six".