642981 has 8 divisors (see below), whose sum is σ = 868480. Its totient is φ = 423072.

The previous prime is 642977. The next prime is 642997. The reversal of 642981 is 189246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 642981 - 2² = 642977 is a prime.

It is a super-2 number, since 2×642981² = 826849132722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 642981.

It is not an unprimeable number, because it can be changed into a prime (642931) 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, 1120 + ... + 1593.

It is an arithmetic number, because the mean of its divisors is an integer number (108560).

2⁶⁴²⁹⁸¹ is an apocalyptic number.

It is an amenable number.

642981 is a deficient number, since it is larger than the sum of its proper divisors (225499).

642981 is a wasteful number, since it uses less digits than its factorization.

642981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2795.

The product of its digits is 3456, while the sum is 30.

The square root of 642981 is about 801.8609605162. The cubic root of 642981 is about 86.3109797708.

The spelling of 642981 in words is "six hundred forty-two thousand, nine hundred eighty-one".