211221993 has 16 divisors (see below), whose sum is σ = 306676800. Its totient is φ = 128802240.

The previous prime is 211221979. The next prime is 211222019. The reversal of 211221993 is 399122112.

It is not a de Polignac number, because 211221993 - 2⁵ = 211221961 is a prime.

It is a super-2 number, since 2×211221993² = 89229460653784098, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 211221993.

It is not an unprimeable number, because it can be changed into a prime (211220993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62238 + ... + 65543.

It is an arithmetic number, because the mean of its divisors is an integer number (19167300).

Almost surely, 2^211221993 is an apocalyptic number.

It is an amenable number.

211221993 is a deficient number, since it is larger than the sum of its proper divisors (95454807).

211221993 is a wasteful number, since it uses less digits than its factorization.

211221993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127832.

The product of its digits is 1944, while the sum is 30.

The square root of 211221993 is about 14533.4783517230. The cubic root of 211221993 is about 595.5428917396.

The spelling of 211221993 in words is "two hundred eleven million, two hundred twenty-one thousand, nine hundred ninety-three".