21398273 has 12 divisors (see below), whose sum is σ = 23617980. Its totient is φ = 19371456.

The previous prime is 21398261. The next prime is 21398281. The reversal of 21398273 is 37289312.

It can be written as a sum of positive squares in 6 ways, for example, as 3564544 + 17833729 = 1888^2 + 4223^2 .

It is not a de Polignac number, because 21398273 - 2⁸ = 21398017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21398233) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7763 + ... + 10151.

It is an arithmetic number, because the mean of its divisors is an integer number (1968165).

Almost surely, 2^21398273 is an apocalyptic number.

It is an amenable number.

21398273 is a deficient number, since it is larger than the sum of its proper divisors (2219707).

21398273 is a wasteful number, since it uses less digits than its factorization.

21398273 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2468 (or 2455 counting only the distinct ones).

The product of its digits is 18144, while the sum is 35.

The square root of 21398273 is about 4625.8267369196. The cubic root of 21398273 is about 277.6256412365.

The spelling of 21398273 in words is "twenty-one million, three hundred ninety-eight thousand, two hundred seventy-three".