21072621851 has 2 divisors, whose sum is σ = 21072621852. Its totient is φ = 21072621850.

The previous prime is 21072621793. The next prime is 21072621853. The reversal of 21072621851 is 15812627012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21072621851 is a prime.

Together with 21072621853, 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 (21072621853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10536310925 + 10536310926.

It is an arithmetic number, because the mean of its divisors is an integer number (10536310926).

Almost surely, 2^21072621851 is an apocalyptic number.

21072621851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21072621851 is an equidigital number, since it uses as much as digits as its factorization.

21072621851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13440, while the sum is 35.

The spelling of 21072621851 in words is "twenty-one billion, seventy-two million, six hundred twenty-one thousand, eight hundred fifty-one".