21147636 has 48 divisors (see below), whose sum is σ = 51565248. Its totient is φ = 6739200.

The previous prime is 21147617. The next prime is 21147647. The reversal of 21147636 is 63674112.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25671 + ... + 26481.

It is an arithmetic number, because the mean of its divisors is an integer number (1074276).

Almost surely, 2^21147636 is an apocalyptic number.

It is an amenable number.

21147636 is an abundant number, since it is smaller than the sum of its proper divisors (30417612).

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

21147636 is a wasteful number, since it uses less digits than its factorization.

21147636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912 (or 910 counting only the distinct ones).

The product of its digits is 6048, while the sum is 30.

The square root of 21147636 is about 4598.6558905837. The cubic root of 21147636 is about 276.5374425956.

The spelling of 21147636 in words is "twenty-one million, one hundred forty-seven thousand, six hundred thirty-six".