681909070209221 has 2 divisors, whose sum is σ = 681909070209222. Its totient is φ = 681909070209220.

The previous prime is 681909070209181. The next prime is 681909070209239. The reversal of 681909070209221 is 122902070909186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620661056824900 + 61248013384321 = 24913070^2 + 7826111^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681909070209221 is a prime.

It is a super-2 number, since 2×681909070209221² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681909070200221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340954535104610 + 340954535104611.

It is an arithmetic number, because the mean of its divisors is an integer number (340954535104611).

Almost surely, 2^{681909070209221} is an apocalyptic number.

It is an amenable number.

681909070209221 is a deficient number, since it is larger than the sum of its proper divisors (1).

681909070209221 is an equidigital number, since it uses as much as digits as its factorization.

681909070209221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1959552, while the sum is 56.

The spelling of 681909070209221 in words is "six hundred eighty-one trillion, nine hundred nine billion, seventy million, two hundred nine thousand, two hundred twenty-one".