21308727 has 16 divisors (see below), whose sum is σ = 31108608. Its totient is φ = 12866880.

The previous prime is 21308723. The next prime is 21308731. The reversal of 21308727 is 72780312.

It is an interprime number because it is at equal distance from previous prime (21308723) and next prime (21308731).

It is not a de Polignac number, because 21308727 - 2² = 21308723 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21308694 and 21308703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9298 + ... + 11360.

It is an arithmetic number, because the mean of its divisors is an integer number (1944288).

Almost surely, 2^21308727 is an apocalyptic number.

21308727 is a deficient number, since it is larger than the sum of its proper divisors (9799881).

21308727 is a wasteful number, since it uses less digits than its factorization.

21308727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2390.

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 21308727 is about 4616.1376712572. The cubic root of 21308727 is about 277.2378369754.

The spelling of 21308727 in words is "twenty-one million, three hundred eight thousand, seven hundred twenty-seven".