21489457 has 4 divisors (see below), whose sum is σ = 23443056. Its totient is φ = 19535860.

The previous prime is 21489451. The next prime is 21489463. The reversal of 21489457 is 75498412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21489451) and next prime (21489463).

It is a cyclic number.

It is not a de Polignac number, because 21489457 - 2³ = 21489449 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21489451) 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, 976783 + ... + 976804.

It is an arithmetic number, because the mean of its divisors is an integer number (5860764).

Almost surely, 2^21489457 is an apocalyptic number.

It is an amenable number.

21489457 is a deficient number, since it is larger than the sum of its proper divisors (1953599).

21489457 is a wasteful number, since it uses less digits than its factorization.

21489457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1953598.

The product of its digits is 80640, while the sum is 40.

The square root of 21489457 is about 4635.6722274121. The cubic root of 21489457 is about 278.0194291409.

The spelling of 21489457 in words is "twenty-one million, four hundred eighty-nine thousand, four hundred fifty-seven".