21146891 has 2 divisors, whose sum is σ = 21146892. Its totient is φ = 21146890.

The previous prime is 21146863. The next prime is 21146903. The reversal of 21146891 is 19864112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21146891 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21146831) 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 as a sum of consecutive naturals, namely, 10573445 + 10573446.

It is an arithmetic number, because the mean of its divisors is an integer number (10573446).

Almost surely, 2^21146891 is an apocalyptic number.

21146891 is a deficient number, since it is larger than the sum of its proper divisors (1).

21146891 is an equidigital number, since it uses as much as digits as its factorization.

21146891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 32.

The square root of 21146891 is about 4598.5748879408. The cubic root of 21146891 is about 276.5341952221.

The spelling of 21146891 in words is "twenty-one million, one hundred forty-six thousand, eight hundred ninety-one".