21685045051 has 2 divisors, whose sum is σ = 21685045052. Its totient is φ = 21685045050.

The previous prime is 21685045043. The next prime is 21685045069. The reversal of 21685045051 is 15054058612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21685045051 - 2³ = 21685045043 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21685045051.

It is not a weakly prime, because it can be changed into another prime (21689045051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10842522525 + 10842522526.

It is an arithmetic number, because the mean of its divisors is an integer number (10842522526).

Almost surely, 2^21685045051 is an apocalyptic number.

21685045051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21685045051 is an equidigital number, since it uses as much as digits as its factorization.

21685045051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48000, while the sum is 37.

The spelling of 21685045051 in words is "twenty-one billion, six hundred eighty-five million, forty-five thousand, fifty-one".