21759013 has 4 divisors (see below), whose sum is σ = 21871948. Its totient is φ = 21646080.

The previous prime is 21759011. The next prime is 21759029. The reversal of 21759013 is 31095712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7935489 + 13823524 = 2817^2 + 3718^2 .

It is a cyclic number.

It is not a de Polignac number, because 21759013 - 2¹ = 21759011 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 (21759011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56178 + ... + 56563.

It is an arithmetic number, because the mean of its divisors is an integer number (5467987).

Almost surely, 2^21759013 is an apocalyptic number.

It is an amenable number.

21759013 is a deficient number, since it is larger than the sum of its proper divisors (112935).

21759013 is a wasteful number, since it uses less digits than its factorization.

21759013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112934.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21759013 is about 4664.6557214868. The cubic root of 21759013 is about 279.1770607352.

The spelling of 21759013 in words is "twenty-one million, seven hundred fifty-nine thousand, thirteen".