21071751851 has 2 divisors, whose sum is σ = 21071751852. Its totient is φ = 21071751850.

The previous prime is 21071751839. The next prime is 21071751901. The reversal of 21071751851 is 15815717012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21071751851 is a prime.

It is not a weakly prime, because it can be changed into another prime (21071750851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10535875925 + 10535875926.

It is an arithmetic number, because the mean of its divisors is an integer number (10535875926).

Almost surely, 2^21071751851 is an apocalyptic number.

21071751851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21071751851 is an equidigital number, since it uses as much as digits as its factorization.

21071751851 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19600, while the sum is 38.

The spelling of 21071751851 in words is "twenty-one billion, seventy-one million, seven hundred fifty-one thousand, eight hundred fifty-one".