644670612540 has 36 divisors (see below), whose sum is σ = 1955500858584. Its totient is φ = 171912163296.

The previous prime is 644670612527. The next prime is 644670612569. The reversal of 644670612540 is 45216076446.

644670612540 is a `hidden beast` number, since 6 + 4 + 46 + 7 + 0 + 61 + 2 + 540 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 1790751522 + ... + 1790751881.

It is an arithmetic number, because the mean of its divisors is an integer number (54319468294).

Almost surely, 2^644670612540 is an apocalyptic number.

644670612540 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644670612540 is an abundant number, since it is smaller than the sum of its proper divisors (1310830246044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644670612540 is a wasteful number, since it uses less digits than its factorization.

644670612540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3581503418 (or 3581503413 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 45.

Adding to 644670612540 its reverse (45216076446), we get a palindrome (689886688986).

The spelling of 644670612540 in words is "six hundred forty-four billion, six hundred seventy million, six hundred twelve thousand, five hundred forty".