21487293 has 6 divisors (see below), whose sum is σ = 31037214. Its totient is φ = 14324856.

The previous prime is 21487283. The next prime is 21487307. The reversal of 21487293 is 39278412.

It can be written as a sum of positive squares in only one way, i.e., 11009124 + 10478169 = 3318^2 + 3237^2 .

It is not a de Polignac number, because 21487293 - 2⁵ = 21487261 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21487243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1193730 + ... + 1193747.

It is an arithmetic number, because the mean of its divisors is an integer number (5172869).

Almost surely, 2^21487293 is an apocalyptic number.

It is an amenable number.

21487293 is a deficient number, since it is larger than the sum of its proper divisors (9549921).

21487293 is a wasteful number, since it uses less digits than its factorization.

21487293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2387483 (or 2387480 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21487293 is about 4635.4388141793. The cubic root of 21487293 is about 278.0100965917.

The spelling of 21487293 in words is "twenty-one million, four hundred eighty-seven thousand, two hundred ninety-three".