21503249 has 4 divisors (see below), whose sum is σ = 22768164. Its totient is φ = 20238336.

The previous prime is 21503227. The next prime is 21503263. The reversal of 21503249 is 94230512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19864849 + 1638400 = 4457^2 + 1280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21503249 - 2⁸ = 21502993 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21503219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 632432 + ... + 632465.

It is an arithmetic number, because the mean of its divisors is an integer number (5692041).

Almost surely, 2^21503249 is an apocalyptic number.

It is an amenable number.

21503249 is a deficient number, since it is larger than the sum of its proper divisors (1264915).

21503249 is a wasteful number, since it uses less digits than its factorization.

21503249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1264914.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21503249 is about 4637.1595831931. The cubic root of 21503249 is about 278.0788943310.

The spelling of 21503249 in words is "twenty-one million, five hundred three thousand, two hundred forty-nine".