642780 has 36 divisors (see below), whose sum is σ = 1950312. Its totient is φ = 171360.

The previous prime is 642779. The next prime is 642791. The reversal of 642780 is 87246.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×642780² = 826332256800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1606 + ... + 1965.

2⁶⁴²⁷⁸⁰ is an apocalyptic number.

642780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

642780 is an abundant number, since it is smaller than the sum of its proper divisors (1307532).

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

642780 is a wasteful number, since it uses less digits than its factorization.

642780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3586 (or 3581 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 642780 is about 801.7356172704. The cubic root of 642780 is about 86.3019850441.

The spelling of 642780 in words is "six hundred forty-two thousand, seven hundred eighty".