21249316 has 24 divisors (see below), whose sum is σ = 41559840. Its totient is φ = 9422400.

The previous prime is 21249313. The next prime is 21249329. The reversal of 21249316 is 61394212.

It is not an unprimeable number, because it can be changed into a prime (21249313) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4086 + ... + 7693.

It is an arithmetic number, because the mean of its divisors is an integer number (1731660).

Almost surely, 2^21249316 is an apocalyptic number.

It is an amenable number.

21249316 is a deficient number, since it is larger than the sum of its proper divisors (20310524).

21249316 is a wasteful number, since it uses less digits than its factorization.

21249316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11835 (or 11833 counting only the distinct ones).

The product of its digits is 2592, while the sum is 28.

The square root of 21249316 is about 4609.6980378328. The cubic root of 21249316 is about 276.9799409421.

Subtracting 21249316 from its reverse (61394212), we obtain a square (40144896 = 6336²).

The spelling of 21249316 in words is "twenty-one million, two hundred forty-nine thousand, three hundred sixteen".