21430636 has 12 divisors (see below), whose sum is σ = 37778328. Its totient is φ = 10636832.

The previous prime is 21430627. The next prime is 21430639. The reversal of 21430636 is 63603412.

It is a self number, because there is not a number n which added to its sum of digits gives 21430636.

It is not an unprimeable number, because it can be changed into a prime (21430639) 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, 19006 + ... + 20101.

It is an arithmetic number, because the mean of its divisors is an integer number (3148194).

Almost surely, 2^21430636 is an apocalyptic number.

It is an amenable number.

21430636 is a deficient number, since it is larger than the sum of its proper divisors (16347692).

21430636 is a wasteful number, since it uses less digits than its factorization.

21430636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39248 (or 39246 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 21430636 is about 4629.3234926931. The cubic root of 21430636 is about 277.7655321654.

The spelling of 21430636 in words is "twenty-one million, four hundred thirty thousand, six hundred thirty-six".