21288464 has 10 divisors (see below), whose sum is σ = 41246430. Its totient is φ = 10644224.

The previous prime is 21288461. The next prime is 21288473. The reversal of 21288464 is 46488212.

It can be written as a sum of positive squares in only one way, i.e., 16483600 + 4804864 = 4060^2 + 2192^2 .

It is not an unprimeable number, because it can be changed into a prime (21288461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665249 + ... + 665280.

It is an arithmetic number, because the mean of its divisors is an integer number (4124643).

Almost surely, 2^21288464 is an apocalyptic number.

It is an amenable number.

21288464 is a deficient number, since it is larger than the sum of its proper divisors (19957966).

21288464 is a wasteful number, since it uses less digits than its factorization.

21288464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1330537 (or 1330531 counting only the distinct ones).

The product of its digits is 24576, while the sum is 35.

The square root of 21288464 is about 4613.9423490113. The cubic root of 21288464 is about 277.1499316476.

The spelling of 21288464 in words is "twenty-one million, two hundred eighty-eight thousand, four hundred sixty-four".