21530456 has 16 divisors (see below), whose sum is σ = 40446000. Its totient is φ = 10744864.

The previous prime is 21530447. The next prime is 21530459. The reversal of 21530456 is 65403512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530459) 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, 2546 + ... + 7038.

It is an arithmetic number, because the mean of its divisors is an integer number (2527875).

Almost surely, 2^21530456 is an apocalyptic number.

It is an amenable number.

21530456 is a deficient number, since it is larger than the sum of its proper divisors (18915544).

21530456 is a wasteful number, since it uses less digits than its factorization.

21530456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5098 (or 5094 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 21530456 is about 4640.0922404625. The cubic root of 21530456 is about 278.1961247378.

Adding to 21530456 its reverse (65403512), we get a palindrome (86933968).

The spelling of 21530456 in words is "twenty-one million, five hundred thirty thousand, four hundred fifty-six".