644663742 has 16 divisors (see below), whose sum is σ = 1289922960. Its totient is φ = 214788672.

The previous prime is 644663731. The next prime is 644663807. The reversal of 644663742 is 247366446.

It is a junction number, because it is equal to n+sod(n) for n = 644663694 and 644663703.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10063 + ... + 37290.

It is an arithmetic number, because the mean of its divisors is an integer number (80620185).

Almost surely, 2^644663742 is an apocalyptic number.

644663742 is an abundant number, since it is smaller than the sum of its proper divisors (645259218).

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

644663742 is a wasteful number, since it uses less digits than its factorization.

644663742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49627.

The product of its digits is 580608, while the sum is 42.

The square root of 644663742 is about 25390.2292624545. The cubic root of 644663742 is about 863.8620884344.

The spelling of 644663742 in words is "six hundred forty-four million, six hundred sixty-three thousand, seven hundred forty-two".