640948869 has 40 divisors (see below), whose sum is σ = 1099512480. Its totient is φ = 367999200.

The previous prime is 640948853. The next prime is 640948933. The reversal of 640948869 is 968849046.

It is not a de Polignac number, because 640948869 - 2⁴ = 640948853 is a prime.

It is a super-2 number, since 2×640948869² = 821630905344758322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640948849) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2002 + ... + 35859.

It is an arithmetic number, because the mean of its divisors is an integer number (27487812).

Almost surely, 2^640948869 is an apocalyptic number.

It is an amenable number.

640948869 is a deficient number, since it is larger than the sum of its proper divisors (458563611).

640948869 is a wasteful number, since it uses less digits than its factorization.

640948869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37903 (or 37894 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The square root of 640948869 is about 25316.9680056677. The cubic root of 640948869 is about 862.1995566033.

It can be divided in two parts, 6409 and 48869, that added together give a triangular number (55278 = T₃₃₂).

The spelling of 640948869 in words is "six hundred forty million, nine hundred forty-eight thousand, eight hundred sixty-nine".