648685391 has 4 divisors (see below), whose sum is σ = 660924792. Its totient is φ = 636445992.

The previous prime is 648685381. The next prime is 648685423. The reversal of 648685391 is 193586846.

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

It is a cyclic number.

It is not a de Polignac number, because 648685391 - 2¹⁰ = 648684367 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 (648685381) 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, 6119621 + ... + 6119726.

It is an arithmetic number, because the mean of its divisors is an integer number (165231198).

Almost surely, 2^648685391 is an apocalyptic number.

648685391 is a deficient number, since it is larger than the sum of its proper divisors (12239401).

648685391 is a wasteful number, since it uses less digits than its factorization.

648685391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12239400.

The product of its digits is 1244160, while the sum is 50.

The square root of 648685391 is about 25469.3029154706. The cubic root of 648685391 is about 865.6547287787.

The spelling of 648685391 in words is "six hundred forty-eight million, six hundred eighty-five thousand, three hundred ninety-one".