21785867 has 2 divisors, whose sum is σ = 21785868. Its totient is φ = 21785866.

The previous prime is 21785851. The next prime is 21785903. The reversal of 21785867 is 76858712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21785867 - 2⁴ = 21785851 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21785767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10892933 + 10892934.

It is an arithmetic number, because the mean of its divisors is an integer number (10892934).

Almost surely, 2^21785867 is an apocalyptic number.

21785867 is a deficient number, since it is larger than the sum of its proper divisors (1).

21785867 is an equidigital number, since it uses as much as digits as its factorization.

21785867 is an evil number, because the sum of its binary digits is even.

The product of its digits is 188160, while the sum is 44.

The square root of 21785867 is about 4667.5332885797. The cubic root of 21785867 is about 279.2918627982.

The spelling of 21785867 in words is "twenty-one million, seven hundred eighty-five thousand, eight hundred sixty-seven".