21307282 has 4 divisors (see below), whose sum is σ = 31960926. Its totient is φ = 10653640.

The previous prime is 21307271. The next prime is 21307283. The reversal of 21307282 is 28270312.

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., 15358561 + 5948721 = 3919^2 + 2439^2 .

It is not an unprimeable number, because it can be changed into a prime (21307283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5326819 + ... + 5326822.

Almost surely, 2^21307282 is an apocalyptic number.

21307282 is a deficient number, since it is larger than the sum of its proper divisors (10653644).

21307282 is a wasteful number, since it uses less digits than its factorization.

21307282 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10653643.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21307282 is about 4615.9811524745. The cubic root of 21307282 is about 277.2315700950.

Adding to 21307282 its reverse (28270312), we get a palindrome (49577594).

The spelling of 21307282 in words is "twenty-one million, three hundred seven thousand, two hundred eighty-two".