21041857 has 2 divisors, whose sum is σ = 21041858. Its totient is φ = 21041856.

The previous prime is 21041827. The next prime is 21041879. The reversal of 21041857 is 75814012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19855936 + 1185921 = 4456^2 + 1089^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21041857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21041807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520928 + 10520929.

It is an arithmetic number, because the mean of its divisors is an integer number (10520929).

Almost surely, 2^21041857 is an apocalyptic number.

It is an amenable number.

21041857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21041857 is an equidigital number, since it uses as much as digits as its factorization.

21041857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21041857 is about 4587.1403946250. The cubic root of 21041857 is about 276.0755980339.

Adding to 21041857 its reverse (75814012), we get a palindrome (96855869).

The spelling of 21041857 in words is "twenty-one million, forty-one thousand, eight hundred fifty-seven".