21519636 has 12 divisors (see below), whose sum is σ = 50212512. Its totient is φ = 7173208.

The previous prime is 21519599. The next prime is 21519677. The reversal of 21519636 is 63691512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21519597 and 21519606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 896640 + ... + 896663.

It is an arithmetic number, because the mean of its divisors is an integer number (4184376).

Almost surely, 2^21519636 is an apocalyptic number.

It is an amenable number.

21519636 is an abundant number, since it is smaller than the sum of its proper divisors (28692876).

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

21519636 is a wasteful number, since it uses less digits than its factorization.

21519636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1793310 (or 1793308 counting only the distinct ones).

The product of its digits is 9720, while the sum is 33.

The square root of 21519636 is about 4638.9261688455. The cubic root of 21519636 is about 278.1495150044.

It can be divided in two parts, 21519 and 636, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21519636 in words is "twenty-one million, five hundred nineteen thousand, six hundred thirty-six".