644403542 has 8 divisors (see below), whose sum is σ = 966713016. Its totient is φ = 322165872.

The previous prime is 644403509. The next prime is 644403559. The reversal of 644403542 is 245304446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 644403499 and 644403508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26858 + ... + 44834.

It is an arithmetic number, because the mean of its divisors is an integer number (120839127).

Almost surely, 2^644403542 is an apocalyptic number.

644403542 is a deficient number, since it is larger than the sum of its proper divisors (322309474).

644403542 is a wasteful number, since it uses less digits than its factorization.

644403542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35902.

The product of its (nonzero) digits is 46080, while the sum is 32.

The square root of 644403542 is about 25385.1047269851. The cubic root of 644403542 is about 863.7458484222.

Adding to 644403542 its reverse (245304446), we get a palindrome (889707988).

The spelling of 644403542 in words is "six hundred forty-four million, four hundred three thousand, five hundred forty-two".