1864118208781 has 2 divisors, whose sum is σ = 1864118208782. Its totient is φ = 1864118208780.

The previous prime is 1864118208763. The next prime is 1864118208809. The reversal of 1864118208781 is 1878028114681.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1200448922500 + 663669286281 = 1095650^2 + 814659^2 .

It is a cyclic number.

It is not a de Polignac number, because 1864118208781 - 2¹⁵ = 1864118176013 is a prime.

It is a super-2 number, since 2×1864118208781² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1864118208751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 932059104390 + 932059104391.

It is an arithmetic number, because the mean of its divisors is an integer number (932059104391).

Almost surely, 2^{1864118208781} is an apocalyptic number.

It is an amenable number.

1864118208781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1864118208781 is an equidigital number, since it uses as much as digits as its factorization.

1864118208781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1376256, while the sum is 55.

The spelling of 1864118208781 in words is "one trillion, eight hundred sixty-four billion, one hundred eighteen million, two hundred eight thousand, seven hundred eighty-one".