21288746 has 4 divisors (see below), whose sum is σ = 31933122. Its totient is φ = 10644372.

The previous prime is 21288739. The next prime is 21288749. The reversal of 21288746 is 64788212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18361225 + 2927521 = 4285^2 + 1711^2 .

It is not an unprimeable number, because it can be changed into a prime (21288749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5322185 + ... + 5322188.

Almost surely, 2^21288746 is an apocalyptic number.

21288746 is a deficient number, since it is larger than the sum of its proper divisors (10644376).

21288746 is a wasteful number, since it uses less digits than its factorization.

21288746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10644375.

The product of its digits is 43008, while the sum is 38.

The square root of 21288746 is about 4613.9729084597. The cubic root of 21288746 is about 277.1511554080.

The spelling of 21288746 in words is "twenty-one million, two hundred eighty-eight thousand, seven hundred forty-six".