640212293761 has 4 divisors (see below), whose sum is σ = 640217666052. Its totient is φ = 640206921472.

The previous prime is 640212293719. The next prime is 640212293767. The reversal of 640212293761 is 167392212046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 167392212046 = 2 ⋅83696106023.

It can be written as a sum of positive squares in 2 ways, for example, as 78265657600 + 561946636161 = 279760^2 + 749631^2 .

It is a cyclic number.

It is not a de Polignac number, because 640212293761 - 2¹⁹ = 640211769473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640212293767) 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, 2503240 + ... + 2747113.

It is an arithmetic number, because the mean of its divisors is an integer number (160054416513).

Almost surely, 2^640212293761 is an apocalyptic number.

It is an amenable number.

640212293761 is a deficient number, since it is larger than the sum of its proper divisors (5372291).

640212293761 is a wasteful number, since it uses less digits than its factorization.

640212293761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5372290.

The product of its (nonzero) digits is 217728, while the sum is 43.

The spelling of 640212293761 in words is "six hundred forty billion, two hundred twelve million, two hundred ninety-three thousand, seven hundred sixty-one".