21319605 has 28 divisors (see below), whose sum is σ = 38364300. Its totient is φ = 11368512.

The previous prime is 21319603. The next prime is 21319607. The reversal of 21319605 is 50691312.

21319605 is a `hidden beast` number, since 21 + 31 + 9 + 605 = 666.

It is an interprime number because it is at equal distance from previous prime (21319603) and next prime (21319607).

It can be written as a sum of positive squares in 2 ways, for example, as 7436529 + 13883076 = 2727^2 + 3726^2 .

It is not a de Polignac number, because 21319605 - 2¹ = 21319603 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21319603) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 721 + ... + 6569.

Almost surely, 2^21319605 is an apocalyptic number.

It is an amenable number.

21319605 is a deficient number, since it is larger than the sum of its proper divisors (17044695).

21319605 is an frugal number, since it uses more digits than its factorization.

21319605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5872 (or 5857 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 21319605 is about 4617.3157786749. The cubic root of 21319605 is about 277.2850051325.

The spelling of 21319605 in words is "twenty-one million, three hundred nineteen thousand, six hundred five".