21421644 has 24 divisors (see below), whose sum is σ = 50369088. Its totient is φ = 7085520.

The previous prime is 21421627. The next prime is 21421657. The reversal of 21421644 is 44612412.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 5242 + ... + 8385.

It is an arithmetic number, because the mean of its divisors is an integer number (2098712).

Almost surely, 2^21421644 is an apocalyptic number.

It is an amenable number.

21421644 is an abundant number, since it is smaller than the sum of its proper divisors (28947444).

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

21421644 is a wasteful number, since it uses less digits than its factorization.

21421644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13765 (or 13763 counting only the distinct ones).

The product of its digits is 1536, while the sum is 24.

The square root of 21421644 is about 4628.3521905750. The cubic root of 21421644 is about 277.7266778654.

The spelling of 21421644 in words is "twenty-one million, four hundred twenty-one thousand, six hundred forty-four".