21259827 has 16 divisors (see below), whose sum is σ = 31888160. Its totient is φ = 14171760.

The previous prime is 21259807. The next prime is 21259829. The reversal of 21259827 is 72895212.

It is not a de Polignac number, because 21259827 - 2⁷ = 21259699 is a prime.

It is a super-3 number, since 3×21259827³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21259791 and 21259800.

It is not an unprimeable number, because it can be changed into a prime (21259829) 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 15 ways as a sum of consecutive naturals, for example, 2674 + ... + 7047.

It is an arithmetic number, because the mean of its divisors is an integer number (1993010).

Almost surely, 2^21259827 is an apocalyptic number.

21259827 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21259827 is a deficient number, since it is larger than the sum of its proper divisors (10628333).

21259827 is an frugal number, since it uses more digits than its factorization.

21259827 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9742 (or 9724 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21259827 is about 4610.8379932503. The cubic root of 21259827 is about 277.0256029022.

The spelling of 21259827 in words is "twenty-one million, two hundred fifty-nine thousand, eight hundred twenty-seven".