21191958 has 12 divisors (see below), whose sum is σ = 45915948. Its totient is φ = 7063980.

The previous prime is 21191923. The next prime is 21191959. The reversal of 21191958 is 85919112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191959) 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, 588648 + ... + 588683.

It is an arithmetic number, because the mean of its divisors is an integer number (3826329).

Almost surely, 2^21191958 is an apocalyptic number.

21191958 is an abundant number, since it is smaller than the sum of its proper divisors (24723990).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21191958 is a wasteful number, since it uses less digits than its factorization.

21191958 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1177339 (or 1177336 counting only the distinct ones).

The product of its digits is 6480, while the sum is 36.

The square root of 21191958 is about 4603.4723850589. The cubic root of 21191958 is about 276.7305002626.

The spelling of 21191958 in words is "twenty-one million, one hundred ninety-one thousand, nine hundred fifty-eight".