21501859 has 2 divisors, whose sum is σ = 21501860. Its totient is φ = 21501858.

The previous prime is 21501827. The next prime is 21501869. The reversal of 21501859 is 95810512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21501859 - 2⁵ = 21501827 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21501859.

It is not a weakly prime, because it can be changed into another prime (21501869) 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, 10750929 + 10750930.

It is an arithmetic number, because the mean of its divisors is an integer number (10750930).

Almost surely, 2^21501859 is an apocalyptic number.

21501859 is a deficient number, since it is larger than the sum of its proper divisors (1).

21501859 is an equidigital number, since it uses as much as digits as its factorization.

21501859 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 21501859 is about 4637.0097045402. The cubic root of 21501859 is about 278.0729023994.

The spelling of 21501859 in words is "twenty-one million, five hundred one thousand, eight hundred fifty-nine".