646810381 has 16 divisors (see below), whose sum is σ = 779304960. Its totient is φ = 525101040.

The previous prime is 646810379. The next prime is 646810427. The reversal of 646810381 is 183018646.

It is a cyclic number.

It is not a de Polignac number, because 646810381 - 2¹ = 646810379 is a prime.

It is a super-2 number, since 2×646810381² = 836727337938730322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 646810381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646810361) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21511 + ... + 41908.

It is an arithmetic number, because the mean of its divisors is an integer number (48706560).

Almost surely, 2^646810381 is an apocalyptic number.

It is an amenable number.

646810381 is a deficient number, since it is larger than the sum of its proper divisors (132494579).

646810381 is a wasteful number, since it uses less digits than its factorization.

646810381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63504.

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 646810381 is about 25432.4670647580. The cubic root of 646810381 is about 864.8198722793.

The spelling of 646810381 in words is "six hundred forty-six million, eight hundred ten thousand, three hundred eighty-one".