21191836 has 12 divisors (see below), whose sum is σ = 37154880. Its totient is φ = 10576160.

The previous prime is 21191831. The next prime is 21191857. The reversal of 21191836 is 63819112.

It is a junction number, because it is equal to n+sod(n) for n = 21191798 and 21191807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191831) 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, 2380 + ... + 6931.

It is an arithmetic number, because the mean of its divisors is an integer number (3096240).

Almost surely, 2^21191836 is an apocalyptic number.

It is an amenable number.

21191836 is a deficient number, since it is larger than the sum of its proper divisors (15963044).

21191836 is a wasteful number, since it uses less digits than its factorization.

21191836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9884 (or 9882 counting only the distinct ones).

The product of its digits is 2592, while the sum is 31.

The square root of 21191836 is about 4603.4591341729. The cubic root of 21191836 is about 276.7299692249.

The spelling of 21191836 in words is "twenty-one million, one hundred ninety-one thousand, eight hundred thirty-six".