642138 has 16 divisors (see below), whose sum is σ = 1467840. Its totient is φ = 183456.

The previous prime is 642133. The next prime is 642149. The reversal of 642138 is 831246.

It is a happy number.

642138 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×642138² = 824682422088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (642133) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7603 + ... + 7686.

It is an arithmetic number, because the mean of its divisors is an integer number (91740).

2⁶⁴²¹³⁸ is an apocalyptic number.

642138 is an abundant number, since it is smaller than the sum of its proper divisors (825702).

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

642138 is a wasteful number, since it uses less digits than its factorization.

642138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15301.

The product of its digits is 1152, while the sum is 24.

The square root of 642138 is about 801.3351358826. The cubic root of 642138 is about 86.2732430532.

It can be divided in two parts, 642 and 138, that added together give a triangular number (780 = T₃₉).

The spelling of 642138 in words is "six hundred forty-two thousand, one hundred thirty-eight".