21530505 has 16 divisors (see below), whose sum is σ = 34714944. Its totient is φ = 11394240.

The previous prime is 21530497. The next prime is 21530513. The reversal of 21530505 is 50503512.

It is an interprime number because it is at equal distance from previous prime (21530497) and next prime (21530513).

It is not a de Polignac number, because 21530505 - 2³ = 21530497 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3514 + ... + 7443.

It is an arithmetic number, because the mean of its divisors is an integer number (2169684).

Almost surely, 2^21530505 is an apocalyptic number.

It is an amenable number.

21530505 is a deficient number, since it is larger than the sum of its proper divisors (13184439).

21530505 is a wasteful number, since it uses less digits than its factorization.

21530505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11096.

The product of its (nonzero) digits is 750, while the sum is 21.

The square root of 21530505 is about 4640.0975205269. The cubic root of 21530505 is about 278.1963357815.

The spelling of 21530505 in words is "twenty-one million, five hundred thirty thousand, five hundred five".