21530515 has 8 divisors (see below), whose sum is σ = 27196560. Its totient is φ = 16317792.

The previous prime is 21530513. The next prime is 21530527. The reversal of 21530515 is 51503512.

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 21530515 - 2¹ = 21530513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21530513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113224 + ... + 113413.

It is an arithmetic number, because the mean of its divisors is an integer number (3399570).

Almost surely, 2^21530515 is an apocalyptic number.

21530515 is a deficient number, since it is larger than the sum of its proper divisors (5666045).

21530515 is a wasteful number, since it uses less digits than its factorization.

21530515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226661.

The product of its (nonzero) digits is 750, while the sum is 22.

The square root of 21530515 is about 4640.0985980903. The cubic root of 21530515 is about 278.1963788516.

The spelling of 21530515 in words is "twenty-one million, five hundred thirty thousand, five hundred fifteen".