640841015 has 4 divisors (see below), whose sum is σ = 769009224. Its totient is φ = 512672808.

The previous prime is 640840979. The next prime is 640841023. The reversal of 640841015 is 510148046.

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

It is a cyclic number.

It is not a de Polignac number, because 640841015 - 2⁶ = 640840951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64084097 + ... + 64084106.

It is an arithmetic number, because the mean of its divisors is an integer number (192252306).

Almost surely, 2^640841015 is an apocalyptic number.

640841015 is a deficient number, since it is larger than the sum of its proper divisors (128168209).

640841015 is a wasteful number, since it uses less digits than its factorization.

640841015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128168208.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 640841015 is about 25314.8378426566. The cubic root of 640841015 is about 862.1511924295.

The spelling of 640841015 in words is "six hundred forty million, eight hundred forty-one thousand, fifteen".