1648729390681 has 4 divisors (see below), whose sum is σ = 1654555289872. Its totient is φ = 1642903491492.

The previous prime is 1648729390657. The next prime is 1648729390699. The reversal of 1648729390681 is 1860939278461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1648729390681 - 2³³ = 1640139456089 is a prime.

It is a super-2 number, since 2×1648729390681² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1648729390601) 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, 2912949171 + ... + 2912949736.

It is an arithmetic number, because the mean of its divisors is an integer number (413638822468).

Almost surely, 2^{1648729390681} is an apocalyptic number.

It is an amenable number.

1648729390681 is a deficient number, since it is larger than the sum of its proper divisors (5825899191).

1648729390681 is an equidigital number, since it uses as much as digits as its factorization.

1648729390681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5825899190.

The product of its (nonzero) digits is 31352832, while the sum is 64.

The spelling of 1648729390681 in words is "one trillion, six hundred forty-eight billion, seven hundred twenty-nine million, three hundred ninety thousand, six hundred eighty-one".