644155532 has 12 divisors (see below), whose sum is σ = 1130523240. Its totient is φ = 321148896.

The previous prime is 644155529. The next prime is 644155553. The reversal of 644155532 is 235551446.

It is a junction number, because it is equal to n+sod(n) for n = 644155492 and 644155501.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230657 + ... + 233432.

It is an arithmetic number, because the mean of its divisors is an integer number (94210270).

Almost surely, 2^644155532 is an apocalyptic number.

It is an amenable number.

644155532 is a deficient number, since it is larger than the sum of its proper divisors (486367708).

644155532 is a wasteful number, since it uses less digits than its factorization.

644155532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464440 (or 464438 counting only the distinct ones).

The product of its digits is 72000, while the sum is 35.

The square root of 644155532 is about 25380.2193055931. The cubic root of 644155532 is about 863.6350249596.

The spelling of 644155532 in words is "six hundred forty-four million, one hundred fifty-five thousand, five hundred thirty-two".