640662901 has 4 divisors (see below), whose sum is σ = 678348972. Its totient is φ = 602976832.

The previous prime is 640662889. The next prime is 640662923. The reversal of 640662901 is 109266046.

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

It can be written as a sum of positive squares in 2 ways, for example, as 582063876 + 58599025 = 24126^2 + 7655^2 .

It is a cyclic number.

It is not a de Polignac number, because 640662901 - 2⁷ = 640662773 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 (640662941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18843010 + ... + 18843043.

It is an arithmetic number, because the mean of its divisors is an integer number (169587243).

Almost surely, 2^640662901 is an apocalyptic number.

It is an amenable number.

640662901 is a deficient number, since it is larger than the sum of its proper divisors (37686071).

640662901 is a wasteful number, since it uses less digits than its factorization.

640662901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37686070.

The product of its (nonzero) digits is 15552, while the sum is 34.

The square root of 640662901 is about 25311.3196218609. The cubic root of 640662901 is about 862.0713102003.

The spelling of 640662901 in words is "six hundred forty million, six hundred sixty-two thousand, nine hundred one".