642171831 has 16 divisors (see below), whose sum is σ = 979353600. Its totient is φ = 366653088.

The previous prime is 642171793. The next prime is 642171833. The reversal of 642171831 is 138171246.

It is not a de Polignac number, because 642171831 - 2¹⁴ = 642155447 is a prime.

It is a super-2 number, since 2×642171831² = 824769321059785122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 642171792 and 642171801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642171833) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14905 + ... + 38813.

It is an arithmetic number, because the mean of its divisors is an integer number (61209600).

Almost surely, 2^642171831 is an apocalyptic number.

642171831 is a deficient number, since it is larger than the sum of its proper divisors (337181769).

642171831 is a wasteful number, since it uses less digits than its factorization.

642171831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25198.

The product of its digits is 8064, while the sum is 33.

The square root of 642171831 is about 25341.1095060970. The cubic root of 642171831 is about 862.7475812668.

The spelling of 642171831 in words is "six hundred forty-two million, one hundred seventy-one thousand, eight hundred thirty-one".