1640517800381 has 4 divisors (see below), whose sum is σ = 1643077111164. Its totient is φ = 1637958489600.

The previous prime is 1640517800351. The next prime is 1640517800393. The reversal of 1640517800381 is 1830087150461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1188174121156 + 452343679225 = 1090034^2 + 672565^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640517800381 - 2³⁸ = 1365639893437 is a prime.

It is a super-2 number, since 2×1640517800381² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640517800351) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1279654430 + ... + 1279655711.

It is an arithmetic number, because the mean of its divisors is an integer number (410769277791).

Almost surely, 2^{1640517800381} is an apocalyptic number.

It is an amenable number.

1640517800381 is a deficient number, since it is larger than the sum of its proper divisors (2559310783).

1640517800381 is an equidigital number, since it uses as much as digits as its factorization.

1640517800381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2559310782.

The product of its (nonzero) digits is 161280, while the sum is 44.

The spelling of 1640517800381 in words is "one trillion, six hundred forty billion, five hundred seventeen million, eight hundred thousand, three hundred eighty-one".