645035465881 has 3 divisors (see below), whose sum is σ = 645036269023. Its totient is φ = 645034662740.

The previous prime is 645035465791. The next prime is 645035465909. The reversal of 645035465881 is 188564530546.

The square root of 645035465881 is 803141.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 638255590281 + 6779875600 = 798909^2 + 82340^2 .

It is not a de Polignac number, because 645035465881 - 2⁹ = 645035465369 is a prime.

It is a super-2 number, since 2×645035465881² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645035435881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 401571 + ... + 1204711.

Almost surely, 2^645035465881 is an apocalyptic number.

645035465881 is the 803141-st square number.

645035465881 is the 401571-st centered octagonal number.

It is an amenable number.

645035465881 is a deficient number, since it is larger than the sum of its proper divisors (803142).

645035465881 is an frugal number, since it uses more digits than its factorization.

645035465881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1606282 (or 803141 counting only the distinct ones).

The product of its (nonzero) digits is 13824000, while the sum is 55.

It can be divided in two parts, 645035 and 465881, that added together give a square (1110916 = 1054²).

The spelling of 645035465881 in words is "six hundred forty-five billion, thirty-five million, four hundred sixty-five thousand, eight hundred eighty-one".