21207884 has 6 divisors (see below), whose sum is σ = 37113804. Its totient is φ = 10603940.

The previous prime is 21207881. The next prime is 21207997. The reversal of 21207884 is 48870212.

It is a self number, because there is not a number n which added to its sum of digits gives 21207884.

It is not an unprimeable number, because it can be changed into a prime (21207881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2650982 + ... + 2650989.

It is an arithmetic number, because the mean of its divisors is an integer number (6185634).

Almost surely, 2^21207884 is an apocalyptic number.

It is an amenable number.

21207884 is a deficient number, since it is larger than the sum of its proper divisors (15905920).

21207884 is a wasteful number, since it uses less digits than its factorization.

21207884 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5301975 (or 5301973 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 21207884 is about 4605.2018413963. The cubic root of 21207884 is about 276.7998049549.

The spelling of 21207884 in words is "twenty-one million, two hundred seven thousand, eight hundred eighty-four".