21530651 has 8 divisors (see below), whose sum is σ = 21969984. Its totient is φ = 21094920.

The previous prime is 21530627. The next prime is 21530669. The reversal of 21530651 is 15603512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21530651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21530671) 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, 13376 + ... + 14898.

It is an arithmetic number, because the mean of its divisors is an integer number (2746248).

Almost surely, 2^21530651 is an apocalyptic number.

21530651 is a deficient number, since it is larger than the sum of its proper divisors (439333).

21530651 is a wasteful number, since it uses less digits than its factorization.

21530651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1801.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21530651 is about 4640.1132529282. The cubic root of 21530651 is about 278.1969646036.

The spelling of 21530651 in words is "twenty-one million, five hundred thirty thousand, six hundred fifty-one".