646042997825 has 24 divisors (see below), whose sum is σ = 824289726456. Its totient is φ = 502062080000.

The previous prime is 646042997819. The next prime is 646042997833. The reversal of 646042997825 is 528799240646.

It is a Cunningham number, because it is equal to 803768²+1.

It can be written as a sum of positive squares in 12 ways, for example, as 25332223921 + 620710773904 = 159161^2 + 787852^2 .

It is not a de Polignac number, because 646042997825 - 2²² = 646038803521 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2279936 + ... + 2547585.

It is an arithmetic number, because the mean of its divisors is an integer number (34345405269).

Almost surely, 2^646042997825 is an apocalyptic number.

It is an amenable number.

646042997825 is a deficient number, since it is larger than the sum of its proper divisors (178246728631).

646042997825 is a wasteful number, since it uses less digits than its factorization.

646042997825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4827685 (or 4827680 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 62.

The spelling of 646042997825 in words is "six hundred forty-six billion, forty-two million, nine hundred ninety-seven thousand, eight hundred twenty-five".