21288493 has 8 divisors (see below), whose sum is σ = 22641920. Its totient is φ = 19958400.

The previous prime is 21288481. The next prime is 21288499. The reversal of 21288493 is 39488212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21288493 - 2⁵ = 21288461 is a prime.

It is a super-2 number, since 2×21288493² = 906399868422098, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288499) 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, 3933 + ... + 7618.

It is an arithmetic number, because the mean of its divisors is an integer number (2830240).

Almost surely, 2^21288493 is an apocalyptic number.

It is an amenable number.

21288493 is a deficient number, since it is larger than the sum of its proper divisors (1353427).

21288493 is a wasteful number, since it uses less digits than its factorization.

21288493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11667.

The product of its digits is 27648, while the sum is 37.

The square root of 21288493 is about 4613.9454916590. The cubic root of 21288493 is about 277.1500574958.

The spelling of 21288493 in words is "twenty-one million, two hundred eighty-eight thousand, four hundred ninety-three".