221129991 has 6 divisors (see below), whose sum is σ = 319410000. Its totient is φ = 147419988.

The previous prime is 221129989. The next prime is 221130001. The reversal of 221129991 is 199921122.

221129991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 221129991 - 2¹ = 221129989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221122991) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12284991 + ... + 12285008.

It is an arithmetic number, because the mean of its divisors is an integer number (53235000).

Almost surely, 2^221129991 is an apocalyptic number.

221129991 is a deficient number, since it is larger than the sum of its proper divisors (98280009).

221129991 is a wasteful number, since it uses less digits than its factorization.

221129991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24570005 (or 24570002 counting only the distinct ones).

The product of its digits is 5832, while the sum is 36.

The square root of 221129991 is about 14870.4401750587. The cubic root of 221129991 is about 604.7128760739.

The spelling of 221129991 in words is "two hundred twenty-one million, one hundred twenty-nine thousand, nine hundred ninety-one".