640378061 has 4 divisors (see below), whose sum is σ = 650876124. Its totient is φ = 629880000.

The previous prime is 640378021. The next prime is 640378073. The reversal of 640378061 is 160873046.

640378061 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 220374025 + 420004036 = 14845^2 + 20494^2 .

It is a cyclic number.

It is not a de Polignac number, because 640378061 - 2¹⁴ = 640361677 is a prime.

It is a super-2 number, since 2×640378061² = 820168122020239442, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640378001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5248940 + ... + 5249061.

It is an arithmetic number, because the mean of its divisors is an integer number (162719031).

Almost surely, 2^640378061 is an apocalyptic number.

640378061 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

640378061 is a deficient number, since it is larger than the sum of its proper divisors (10498063).

640378061 is a wasteful number, since it uses less digits than its factorization.

640378061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10498062.

The product of its (nonzero) digits is 24192, while the sum is 35.

The square root of 640378061 is about 25305.6922647850. The cubic root of 640378061 is about 861.9435317219.

The spelling of 640378061 in words is "six hundred forty million, three hundred seventy-eight thousand, sixty-one".