645236205415551 has 32 divisors (see below), whose sum is σ = 1006219462860800. Its totient is φ = 407516324382720.

The previous prime is 645236205415531. The next prime is 645236205415559. The reversal of 645236205415551 is 155514502632546.

645236205415551 is a `hidden beast` number, since 6 + 4 + 5 + 2 + 3 + 6 + 20 + 54 + 15 + 551 = 666.

It is not a de Polignac number, because 645236205415551 - 2³⁵ = 645201845677183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645236205415559) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 177528831 + ... + 181126911.

It is an arithmetic number, because the mean of its divisors is an integer number (31444358214400).

Almost surely, 2^{645236205415551} is an apocalyptic number.

645236205415551 is a deficient number, since it is larger than the sum of its proper divisors (360983257445249).

645236205415551 is a wasteful number, since it uses less digits than its factorization.

645236205415551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3947676 (or 3947670 counting only the distinct ones).

The product of its (nonzero) digits is 21600000, while the sum is 54.

The spelling of 645236205415551 in words is "six hundred forty-five trillion, two hundred thirty-six billion, two hundred five million, four hundred fifteen thousand, five hundred fifty-one".