638503945 has 4 divisors (see below), whose sum is σ = 766204740. Its totient is φ = 510803152.

The previous prime is 638503939. The next prime is 638503951. The reversal of 638503945 is 549305836.

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

It is an interprime number because it is at equal distance from previous prime (638503939) and next prime (638503951).

It can be written as a sum of positive squares in 2 ways, for example, as 205406224 + 433097721 = 14332^2 + 20811^2 .

It is a cyclic number.

It is not a de Polignac number, because 638503945 - 2¹⁵ = 638471177 is a prime.

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, 63850390 + ... + 63850399.

It is an arithmetic number, because the mean of its divisors is an integer number (191551185).

Almost surely, 2^638503945 is an apocalyptic number.

It is an amenable number.

638503945 is a deficient number, since it is larger than the sum of its proper divisors (127700795).

638503945 is a wasteful number, since it uses less digits than its factorization.

638503945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127700794.

The product of its (nonzero) digits is 388800, while the sum is 43.

The square root of 638503945 is about 25268.6355983065. The cubic root of 638503945 is about 861.1018619456.

The spelling of 638503945 in words is "six hundred thirty-eight million, five hundred three thousand, nine hundred forty-five".