211121991 has 32 divisors (see below), whose sum is σ = 329472000. Its totient is φ = 133350624.

The previous prime is 211121987. The next prime is 211122007. The reversal of 211121991 is 199121112.

It is not a de Polignac number, because 211121991 - 2² = 211121987 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211121971) 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, 66130 + ... + 69248.

It is an arithmetic number, because the mean of its divisors is an integer number (10296000).

Almost surely, 2^211121991 is an apocalyptic number.

211121991 is a deficient number, since it is larger than the sum of its proper divisors (118350009).

211121991 is a wasteful number, since it uses less digits than its factorization.

211121991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3260 (or 3254 counting only the distinct ones).

The product of its digits is 324, while the sum is 27.

The square root of 211121991 is about 14530.0375429660. The cubic root of 211121991 is about 595.4488912986.

The spelling of 211121991 in words is "two hundred eleven million, one hundred twenty-one thousand, nine hundred ninety-one".