646440621 has 4 divisors (see below), whose sum is σ = 861920832. Its totient is φ = 430960412.

The previous prime is 646440611. The next prime is 646440637. The reversal of 646440621 is 126044646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 646440621 - 2⁷ = 646440493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646440611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107740101 + ... + 107740106.

It is an arithmetic number, because the mean of its divisors is an integer number (215480208).

Almost surely, 2^646440621 is an apocalyptic number.

It is an amenable number.

646440621 is a deficient number, since it is larger than the sum of its proper divisors (215480211).

646440621 is a wasteful number, since it uses less digits than its factorization.

646440621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215480210.

The product of its (nonzero) digits is 27648, while the sum is 33.

The square root of 646440621 is about 25425.1965774112. The cubic root of 646440621 is about 864.6550446060.

The spelling of 646440621 in words is "six hundred forty-six million, four hundred forty thousand, six hundred twenty-one".