501638905 has 8 divisors (see below), whose sum is σ = 613324872. Its totient is φ = 393739008.

The previous prime is 501638843. The next prime is 501638959. The reversal of 501638905 is 509836105.

It can be written as a sum of positive squares in 4 ways, for example, as 144769024 + 356869881 = 12032^2 + 18891^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 501638905 - 2⁷ = 501638777 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 946224 + ... + 946753.

It is an arithmetic number, because the mean of its divisors is an integer number (76665609).

Almost surely, 2^501638905 is an apocalyptic number.

It is an amenable number.

501638905 is a deficient number, since it is larger than the sum of its proper divisors (111685967).

501638905 is a wasteful number, since it uses less digits than its factorization.

501638905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1893035.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 501638905 is about 22397.2968235008. The cubic root of 501638905 is about 794.5667800407.

It can be divided in two parts, 50 and 1638905, that added together give a triangular number (1638955 = T₁₈₁₀).

The spelling of 501638905 in words is "five hundred one million, six hundred thirty-eight thousand, nine hundred five".