1638649535 has 4 divisors (see below), whose sum is σ = 1966379448. Its totient is φ = 1310919624.

The previous prime is 1638649511. The next prime is 1638649543. The reversal of 1638649535 is 5359468361.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5359468361 = 13 ⋅412266797.

It is a cyclic number.

It is not a de Polignac number, because 1638649535 - 2¹⁰ = 1638648511 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, 163864949 + ... + 163864958.

It is an arithmetic number, because the mean of its divisors is an integer number (491594862).

Almost surely, 2^1638649535 is an apocalyptic number.

1638649535 is a deficient number, since it is larger than the sum of its proper divisors (327729913).

1638649535 is an equidigital number, since it uses as much as digits as its factorization.

1638649535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327729912.

The product of its digits is 2332800, while the sum is 50.

The square root of 1638649535 is about 40480.2363505946. The cubic root of 1638649535 is about 1178.9499264486.

The spelling of 1638649535 in words is "one billion, six hundred thirty-eight million, six hundred forty-nine thousand, five hundred thirty-five".