640999461 has 16 divisors (see below), whose sum is σ = 864269120. Its totient is φ = 422547840.

The previous prime is 640999459. The next prime is 640999477. The reversal of 640999461 is 164999046.

It is not a de Polignac number, because 640999461 - 2¹ = 640999459 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640999461.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640999421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 185001 + ... + 188433.

It is an arithmetic number, because the mean of its divisors is an integer number (54016820).

Almost surely, 2^640999461 is an apocalyptic number.

It is an amenable number.

640999461 is a deficient number, since it is larger than the sum of its proper divisors (223269659).

640999461 is a wasteful number, since it uses less digits than its factorization.

640999461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4116.

The product of its (nonzero) digits is 419904, while the sum is 48.

The square root of 640999461 is about 25317.9671577321. The cubic root of 640999461 is about 862.2222413313. Note that the first 4 decimals are identical.

The spelling of 640999461 in words is "six hundred forty million, nine hundred ninety-nine thousand, four hundred sixty-one".