211220021999 has 4 divisors (see below), whose sum is σ = 241394310864. Its totient is φ = 181045733136.

The previous prime is 211220021981. The next prime is 211220022011. The reversal of 211220021999 is 999120022112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 211220021999 - 2¹⁶ = 211219956463 is a prime.

It is a super-2 number, since 2×211220021999² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211220321999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15087144422 + ... + 15087144435.

It is an arithmetic number, because the mean of its divisors is an integer number (60348577716).

Almost surely, 2^211220021999 is an apocalyptic number.

211220021999 is a deficient number, since it is larger than the sum of its proper divisors (30174288865).

211220021999 is an equidigital number, since it uses as much as digits as its factorization.

211220021999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30174288864.

The product of its (nonzero) digits is 11664, while the sum is 38.

The spelling of 211220021999 in words is "two hundred eleven billion, two hundred twenty million, twenty-one thousand, nine hundred ninety-nine".