641810978 has 4 divisors (see below), whose sum is σ = 962716470. Its totient is φ = 320905488.

The previous prime is 641810881. The next prime is 641810989. The reversal of 641810978 is 879018146.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 879018146 = 2 ⋅439509073.

It can be written as a sum of positive squares in only one way, i.e., 545829769 + 95981209 = 23363^2 + 9797^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160452743 + ... + 160452746.

Almost surely, 2^641810978 is an apocalyptic number.

641810978 is a deficient number, since it is larger than the sum of its proper divisors (320905492).

641810978 is a wasteful number, since it uses less digits than its factorization.

641810978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320905491.

The product of its (nonzero) digits is 96768, while the sum is 44.

The square root of 641810978 is about 25333.9885924029. The cubic root of 641810978 is about 862.5859509107.

The spelling of 641810978 in words is "six hundred forty-one million, eight hundred ten thousand, nine hundred seventy-eight".