21542613 has 16 divisors (see below), whose sum is σ = 30345216. Its totient is φ = 13572720.

The previous prime is 21542597. The next prime is 21542623. The reversal of 21542613 is 31624512.

It is not a de Polignac number, because 21542613 - 2⁴ = 21542597 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542623) 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 15 ways as a sum of consecutive naturals, for example, 1306 + ... + 6692.

It is an arithmetic number, because the mean of its divisors is an integer number (1896576).

Almost surely, 2^21542613 is an apocalyptic number.

It is an amenable number.

21542613 is a deficient number, since it is larger than the sum of its proper divisors (8802603).

21542613 is a wasteful number, since it uses less digits than its factorization.

21542613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5464.

The product of its digits is 1440, while the sum is 24.

The square root of 21542613 is about 4641.4020511048. The cubic root of 21542613 is about 278.2484752925.

It can be divided in two parts, 21542 and 613, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21542613 in words is "twenty-one million, five hundred forty-two thousand, six hundred thirteen".