21407644 has 12 divisors (see below), whose sum is σ = 37583784. Its totient is φ = 10669424.

The previous prime is 21407629. The next prime is 21407647. The reversal of 21407644 is 44670412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21407647) 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 3 ways as a sum of consecutive naturals, for example, 7174 + ... + 9709.

It is an arithmetic number, because the mean of its divisors is an integer number (3131982).

Almost surely, 2^21407644 is an apocalyptic number.

It is an amenable number.

21407644 is a deficient number, since it is larger than the sum of its proper divisors (16176140).

21407644 is a wasteful number, since it uses less digits than its factorization.

21407644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17204 (or 17202 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 28.

The square root of 21407644 is about 4626.8395260696. The cubic root of 21407644 is about 277.6661624224. Note that the first 3 decimals are identical.

The spelling of 21407644 in words is "twenty-one million, four hundred seven thousand, six hundred forty-four".