21783628 has 24 divisors (see below), whose sum is σ = 39972240. Its totient is φ = 10375680.

The previous prime is 21783617. The next prime is 21783631. The reversal of 21783628 is 82638712.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5508 + ... + 8596.

It is an arithmetic number, because the mean of its divisors is an integer number (1665510).

Almost surely, 2^21783628 is an apocalyptic number.

It is an amenable number.

21783628 is a deficient number, since it is larger than the sum of its proper divisors (18188612).

21783628 is a wasteful number, since it uses less digits than its factorization.

21783628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3177 (or 3175 counting only the distinct ones).

The product of its digits is 32256, while the sum is 37.

The square root of 21783628 is about 4667.2934341008. The cubic root of 21783628 is about 279.2822945782.

It can be divided in two parts, 217 and 83628, that added together give a triangular number (83845 = T₄₀₉).

The spelling of 21783628 in words is "twenty-one million, seven hundred eighty-three thousand, six hundred twenty-eight".