21099003857 has 2 divisors, whose sum is σ = 21099003858. Its totient is φ = 21099003856.

The previous prime is 21099003847. The next prime is 21099003859. The reversal of 21099003857 is 75830099012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21097272001 + 1731856 = 145249^2 + 1316^2 .

It is a cyclic number.

It is not a de Polignac number, because 21099003857 - 2²⁶ = 21031894993 is a prime.

Together with 21099003859, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21099003859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549501928 + 10549501929.

It is an arithmetic number, because the mean of its divisors is an integer number (10549501929).

Almost surely, 2^21099003857 is an apocalyptic number.

It is an amenable number.

21099003857 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099003857 is an equidigital number, since it uses as much as digits as its factorization.

21099003857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 44.

The spelling of 21099003857 in words is "twenty-one billion, ninety-nine million, three thousand, eight hundred fifty-seven".