1640407654681 has 2 divisors, whose sum is σ = 1640407654682. Its totient is φ = 1640407654680.

The previous prime is 1640407654651. The next prime is 1640407654693. The reversal of 1640407654681 is 1864567040461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1640407654656 + 25 = 1280784^2 + 5^2 .

It is an emirp because it is prime and its reverse (1864567040461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1640407654681 - 2⁹ = 1640407654169 is a prime.

It is a super-3 number, since 3×1640407654681³ (a number of 38 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (1640407654651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 820203827340 + 820203827341.

It is an arithmetic number, because the mean of its divisors is an integer number (820203827341).

Almost surely, 2^{1640407654681} is an apocalyptic number.

It is an amenable number.

1640407654681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1640407654681 is an equidigital number, since it uses as much as digits as its factorization.

1640407654681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3870720, while the sum is 52.

The spelling of 1640407654681 in words is "one trillion, six hundred forty billion, four hundred seven million, six hundred fifty-four thousand, six hundred eighty-one".