641978 has 8 divisors (see below), whose sum is σ = 986580. Its totient is φ = 313120.

The previous prime is 641969. The next prime is 641981. The reversal of 641978 is 879146.

It can be written as a sum of positive squares in 2 ways, for example, as 499849 + 142129 = 707^2 + 377^2 .

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3833 + ... + 3996.

2⁶⁴¹⁹⁷⁸ is an apocalyptic number.

641978 is a deficient number, since it is larger than the sum of its proper divisors (344602).

641978 is a wasteful number, since it uses less digits than its factorization.

641978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7872.

The product of its digits is 12096, while the sum is 35.

The square root of 641978 is about 801.2352962769. The cubic root of 641978 is about 86.2660769583.

The spelling of 641978 in words is "six hundred forty-one thousand, nine hundred seventy-eight".