21764144 has 10 divisors (see below), whose sum is σ = 42168060. Its totient is φ = 10882064.

The previous prime is 21764143. The next prime is 21764179. The reversal of 21764144 is 44146712.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21764143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 680114 + ... + 680145.

It is an arithmetic number, because the mean of its divisors is an integer number (4216806).

Almost surely, 2^21764144 is an apocalyptic number.

It is an amenable number.

21764144 is a deficient number, since it is larger than the sum of its proper divisors (20403916).

21764144 is a wasteful number, since it uses less digits than its factorization.

21764144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1360267 (or 1360261 counting only the distinct ones).

The product of its digits is 5376, while the sum is 29.

The square root of 21764144 is about 4665.2056760662. The cubic root of 21764144 is about 279.1990032887.

The spelling of 21764144 in words is "twenty-one million, seven hundred sixty-four thousand, one hundred forty-four".