21307827 has 4 divisors (see below), whose sum is σ = 28410440. Its totient is φ = 14205216.

The previous prime is 21307813. The next prime is 21307829. The reversal of 21307827 is 72870312.

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

It is a de Polignac number, because none of the positive numbers 2^k-21307827 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21307794 and 21307803.

It is not an unprimeable number, because it can be changed into a prime (21307829) 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, 3551302 + ... + 3551307.

It is an arithmetic number, because the mean of its divisors is an integer number (7102610).

Almost surely, 2^21307827 is an apocalyptic number.

21307827 is a deficient number, since it is larger than the sum of its proper divisors (7102613).

21307827 is an equidigital number, since it uses as much as digits as its factorization.

21307827 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7102612.

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

The square root of 21307827 is about 4616.0401861336. The cubic root of 21307827 is about 277.2339337613.

The spelling of 21307827 in words is "twenty-one million, three hundred seven thousand, eight hundred twenty-seven".