21307593 has 4 divisors (see below), whose sum is σ = 28410128. Its totient is φ = 14205060.

The previous prime is 21307589. The next prime is 21307609. The reversal of 21307593 is 39570312.

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 not a de Polignac number, because 21307593 - 2² = 21307589 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21307593.

It is not an unprimeable number, because it can be changed into a prime (21307553) 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, 3551263 + ... + 3551268.

It is an arithmetic number, because the mean of its divisors is an integer number (7102532).

Almost surely, 2^21307593 is an apocalyptic number.

It is an amenable number.

21307593 is a deficient number, since it is larger than the sum of its proper divisors (7102535).

21307593 is an equidigital number, since it uses as much as digits as its factorization.

21307593 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7102534.

The product of its (nonzero) digits is 5670, while the sum is 30.

The square root of 21307593 is about 4616.0148396642. The cubic root of 21307593 is about 277.2329189077.

The spelling of 21307593 in words is "twenty-one million, three hundred seven thousand, five hundred ninety-three".