21447866 has 16 divisors (see below), whose sum is σ = 35317728. Its totient is φ = 9687600.

The previous prime is 21447859. The next prime is 21447869. The reversal of 21447866 is 66874412.

It is not an unprimeable number, because it can be changed into a prime (21447869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 596 + ... + 6576.

It is an arithmetic number, because the mean of its divisors is an integer number (2207358).

Almost surely, 2^21447866 is an apocalyptic number.

21447866 is a deficient number, since it is larger than the sum of its proper divisors (13869862).

21447866 is a wasteful number, since it uses less digits than its factorization.

21447866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6157.

The product of its digits is 64512, while the sum is 38.

The square root of 21447866 is about 4631.1840818521. The cubic root of 21447866 is about 277.8399523877.

The spelling of 21447866 in words is "twenty-one million, four hundred forty-seven thousand, eight hundred sixty-six".