642635131 has 4 divisors (see below), whose sum is σ = 642755664. Its totient is φ = 642514600.

The previous prime is 642635117. The next prime is 642635141. The reversal of 642635131 is 131536246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 131536246 = 2 ⋅65768123.

It is a cyclic number.

It is not a de Polignac number, because 642635131 - 2¹¹ = 642633083 is a prime.

It is a super-2 number, since 2×642635131² = 825959823190774322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642635093 and 642635102.

It is not an unprimeable number, because it can be changed into a prime (642635101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51880 + ... + 63061.

It is an arithmetic number, because the mean of its divisors is an integer number (160688916).

Almost surely, 2^642635131 is an apocalyptic number.

642635131 is a deficient number, since it is larger than the sum of its proper divisors (120533).

642635131 is a wasteful number, since it uses less digits than its factorization.

642635131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120532.

The product of its digits is 12960, while the sum is 31.

The square root of 642635131 is about 25350.2491309257. The cubic root of 642635131 is about 862.9550101037.

The spelling of 642635131 in words is "six hundred forty-two million, six hundred thirty-five thousand, one hundred thirty-one".