21542013 has 12 divisors (see below), whose sum is σ = 31232188. Its totient is φ = 14307840.

The previous prime is 21541979. The next prime is 21542063. The reversal of 21542013 is 31024512.

It can be written as a sum of positive squares in 2 ways, for example, as 1855044 + 19686969 = 1362^2 + 4437^2 .

It is not a de Polignac number, because 21542013 - 2¹² = 21537917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542063) 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 11 ways as a sum of consecutive naturals, for example, 1828 + ... + 6813.

Almost surely, 2^21542013 is an apocalyptic number.

It is an amenable number.

21542013 is a deficient number, since it is larger than the sum of its proper divisors (9690175).

21542013 is a wasteful number, since it uses less digits than its factorization.

21542013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8924 (or 8921 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21542013 is about 4641.3374150130. The cubic root of 21542013 is about 278.2458920306.

Adding to 21542013 its reverse (31024512), we get a palindrome (52566525).

The spelling of 21542013 in words is "twenty-one million, five hundred forty-two thousand, thirteen".