6921861460781 has 2 divisors, whose sum is σ = 6921861460782. Its totient is φ = 6921861460780.

The previous prime is 6921861460729. The next prime is 6921861460807. The reversal of 6921861460781 is 1870641681296.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5287194372100 + 1634667088681 = 2299390^2 + 1278541^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6921861460781 is a prime.

It is a super-2 number, since 2×6921861460781² (a number of 26 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6921861460781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6921861460681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3460930730390 + 3460930730391.

It is an arithmetic number, because the mean of its divisors is an integer number (3460930730391).

Almost surely, 2^{6921861460781} is an apocalyptic number.

It is an amenable number.

6921861460781 is a deficient number, since it is larger than the sum of its proper divisors (1).

6921861460781 is an equidigital number, since it uses as much as digits as its factorization.

6921861460781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6967296, while the sum is 59.

The spelling of 6921861460781 in words is "six trillion, nine hundred twenty-one billion, eight hundred sixty-one million, four hundred sixty thousand, seven hundred eighty-one".