640265471 has 4 divisors (see below), whose sum is σ = 655881744. Its totient is φ = 624649200.

The previous prime is 640265453. The next prime is 640265489. The reversal of 640265471 is 174562046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 174562046 = 2 ⋅87281023.

It is an interprime number because it is at equal distance from previous prime (640265453) and next prime (640265489).

It is a cyclic number.

It is not a de Polignac number, because 640265471 - 2¹⁸ = 640003327 is a prime.

It is a super-3 number, since 3×640265471³ (a number of 27 digits) contains 333 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 (640265411) 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, 7808075 + ... + 7808156.

It is an arithmetic number, because the mean of its divisors is an integer number (163970436).

Almost surely, 2^640265471 is an apocalyptic number.

640265471 is a deficient number, since it is larger than the sum of its proper divisors (15616273).

640265471 is a wasteful number, since it uses less digits than its factorization.

640265471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15616272.

The product of its (nonzero) digits is 40320, while the sum is 35.

The square root of 640265471 is about 25303.4675686950. The cubic root of 640265471 is about 861.8930136940.

The spelling of 640265471 in words is "six hundred forty million, two hundred sixty-five thousand, four hundred seventy-one".