21607493 has 4 divisors (see below), whose sum is σ = 22878540. Its totient is φ = 20336448.

The previous prime is 21607477. The next prime is 21607499. The reversal of 21607493 is 39470612.

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 20052484 + 1555009 = 4478^2 + 1247^2 .

It is a cyclic number.

It is not a de Polignac number, because 21607493 - 2⁴ = 21607477 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 (21607499) 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, 635498 + ... + 635531.

It is an arithmetic number, because the mean of its divisors is an integer number (5719635).

Almost surely, 2^21607493 is an apocalyptic number.

It is an amenable number.

21607493 is a deficient number, since it is larger than the sum of its proper divisors (1271047).

21607493 is a wasteful number, since it uses less digits than its factorization.

21607493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1271046.

The product of its (nonzero) digits is 9072, while the sum is 32.

The square root of 21607493 is about 4648.3860640011. The cubic root of 21607493 is about 278.5275294652.

The spelling of 21607493 in words is "twenty-one million, six hundred seven thousand, four hundred ninety-three".