21276891 has 8 divisors (see below), whose sum is σ = 31521360. Its totient is φ = 14184576.

The previous prime is 21276859. The next prime is 21276907. The reversal of 21276891 is 19867212.

It is not a de Polignac number, because 21276891 - 2⁵ = 21276859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21276821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 393990 + ... + 394043.

It is an arithmetic number, because the mean of its divisors is an integer number (3940170).

Almost surely, 2^21276891 is an apocalyptic number.

21276891 is a deficient number, since it is larger than the sum of its proper divisors (10244469).

21276891 is an equidigital number, since it uses as much as digits as its factorization.

21276891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788042 (or 788036 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21276891 is about 4612.6880449473. The cubic root of 21276891 is about 277.0997004120.

The spelling of 21276891 in words is "twenty-one million, two hundred seventy-six thousand, eight hundred ninety-one".