640455061 has 4 divisors (see below), whose sum is σ = 649228492. Its totient is φ = 631681632.

The previous prime is 640455047. The next prime is 640455083. The reversal of 640455061 is 160554046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 160554046 = 2 ⋅80277023.

It can be written as a sum of positive squares in 2 ways, for example, as 471714961 + 168740100 = 21719^2 + 12990^2 .

It is a cyclic number.

It is not a de Polignac number, because 640455061 - 2⁷ = 640454933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640455001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4386606 + ... + 4386751.

It is an arithmetic number, because the mean of its divisors is an integer number (162307123).

Almost surely, 2^640455061 is an apocalyptic number.

It is an amenable number.

640455061 is a deficient number, since it is larger than the sum of its proper divisors (8773431).

640455061 is an equidigital number, since it uses as much as digits as its factorization.

640455061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8773430.

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 640455061 is about 25307.2136158843. The cubic root of 640455061 is about 861.9780774567.

The spelling of 640455061 in words is "six hundred forty million, four hundred fifty-five thousand, sixty-one".