644142535 has 4 divisors (see below), whose sum is σ = 772971048. Its totient is φ = 515314024.

The previous prime is 644142481. The next prime is 644142553. The reversal of 644142535 is 535241446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 535241446 = 2 ⋅267620723.

It is a cyclic number.

It is not a de Polignac number, because 644142535 - 2⁷ = 644142407 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644142535.

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, 64414249 + ... + 64414258.

It is an arithmetic number, because the mean of its divisors is an integer number (193242762).

Almost surely, 2^644142535 is an apocalyptic number.

644142535 is a deficient number, since it is larger than the sum of its proper divisors (128828513).

644142535 is a wasteful number, since it uses less digits than its factorization.

644142535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128828512.

The product of its digits is 57600, while the sum is 34.

The square root of 644142535 is about 25379.9632584446. The cubic root of 644142535 is about 863.6292164556.

The spelling of 644142535 in words is "six hundred forty-four million, one hundred forty-two thousand, five hundred thirty-five".