21361539 has 8 divisors (see below), whose sum is σ = 28514320. Its totient is φ = 14224896.

The previous prime is 21361519. The next prime is 21361579. The reversal of 21361539 is 93516312.

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

It is not a de Polignac number, because 21361539 - 2⁸ = 21361283 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21361519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502 + ... + 6555.

It is an arithmetic number, because the mean of its divisors is an integer number (3564290).

Almost surely, 2^21361539 is an apocalyptic number.

21361539 is a deficient number, since it is larger than the sum of its proper divisors (7152781).

21361539 is a wasteful number, since it uses less digits than its factorization.

21361539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8069.

The product of its digits is 4860, while the sum is 30.

The square root of 21361539 is about 4621.8544979261. The cubic root of 21361539 is about 277.4666853927.

The spelling of 21361539 in words is "twenty-one million, three hundred sixty-one thousand, five hundred thirty-nine".