21385613 has 4 divisors (see below), whose sum is σ = 21399168. Its totient is φ = 21372060.

The previous prime is 21385603. The next prime is 21385627. The reversal of 21385613 is 31658312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21385613 - 2⁴ = 21385597 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 (21385603) 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 3 ways as a sum of consecutive naturals, for example, 4043 + ... + 7688.

It is an arithmetic number, because the mean of its divisors is an integer number (5349792).

Almost surely, 2^21385613 is an apocalyptic number.

It is an amenable number.

21385613 is a deficient number, since it is larger than the sum of its proper divisors (13555).

21385613 is a wasteful number, since it uses less digits than its factorization.

21385613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13554.

The product of its digits is 4320, while the sum is 29.

The square root of 21385613 is about 4624.4581304192. The cubic root of 21385613 is about 277.5708792783.

The spelling of 21385613 in words is "twenty-one million, three hundred eighty-five thousand, six hundred thirteen".