21684654 has 24 divisors (see below), whose sum is σ = 48130992. Its totient is φ = 7051680.

The previous prime is 21684647. The next prime is 21684659. The reversal of 21684654 is 45648612.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21684659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13954 + ... + 15429.

It is an arithmetic number, because the mean of its divisors is an integer number (2005458).

Almost surely, 2^21684654 is an apocalyptic number.

21684654 is an abundant number, since it is smaller than the sum of its proper divisors (26446338).

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

21684654 is a wasteful number, since it uses less digits than its factorization.

21684654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29432 (or 29429 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 21684654 is about 4656.6784299541. The cubic root of 21684654 is about 278.8586789591.

The spelling of 21684654 in words is "twenty-one million, six hundred eighty-four thousand, six hundred fifty-four".