21404464 has 10 divisors (see below), whose sum is σ = 41471180. Its totient is φ = 10702224.

The previous prime is 21404459. The next prime is 21404491. The reversal of 21404464 is 46440412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 668874 + ... + 668905.

It is an arithmetic number, because the mean of its divisors is an integer number (4147118).

Almost surely, 2^21404464 is an apocalyptic number.

It is an amenable number.

21404464 is a deficient number, since it is larger than the sum of its proper divisors (20066716).

21404464 is a wasteful number, since it uses less digits than its factorization.

21404464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1337787 (or 1337781 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 25.

The square root of 21404464 is about 4626.4958662037. The cubic root of 21404464 is about 277.6524130950.

Adding to 21404464 its reverse (46440412), we get a palindrome (67844876).

The spelling of 21404464 in words is "twenty-one million, four hundred four thousand, four hundred sixty-four".