20851867 has 2 divisors, whose sum is σ = 20851868. Its totient is φ = 20851866.

The previous prime is 20851801. The next prime is 20851891. The reversal of 20851867 is 76815802.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20851867 is a prime.

It is not a weakly prime, because it can be changed into another prime (20851267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10425933 + 10425934.

It is an arithmetic number, because the mean of its divisors is an integer number (10425934).

Almost surely, 2^20851867 is an apocalyptic number.

20851867 is a deficient number, since it is larger than the sum of its proper divisors (1).

20851867 is an equidigital number, since it uses as much as digits as its factorization.

20851867 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 20851867 is about 4566.3844560002. The cubic root of 20851867 is about 275.2421756489.

The spelling of 20851867 in words is "twenty million, eight hundred fifty-one thousand, eight hundred sixty-seven".