646019391 has 4 divisors (see below), whose sum is σ = 861359192. Its totient is φ = 430679592.

The previous prime is 646019359. The next prime is 646019393. The reversal of 646019391 is 193910646.

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

It is not a de Polignac number, because 646019391 - 2⁵ = 646019359 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 (646019393) 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, 107669896 + ... + 107669901.

It is an arithmetic number, because the mean of its divisors is an integer number (215339798).

Almost surely, 2^646019391 is an apocalyptic number.

646019391 is a deficient number, since it is larger than the sum of its proper divisors (215339801).

646019391 is a wasteful number, since it uses less digits than its factorization.

646019391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215339800.

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 646019391 is about 25416.9115157605. The cubic root of 646019391 is about 864.4671965803.

The spelling of 646019391 in words is "six hundred forty-six million, nineteen thousand, three hundred ninety-one".