643149621 has 24 divisors (see below), whose sum is σ = 970781760. Its totient is φ = 409533696.

The previous prime is 643149587. The next prime is 643149631. The reversal of 643149621 is 126941346.

643149621 is a `hidden beast` number, since 643 + 1 + 4 + 9 + 6 + 2 + 1 = 666.

It is not a de Polignac number, because 643149621 - 2¹¹ = 643147573 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643149631) 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 23 ways as a sum of consecutive naturals, for example, 176005 + ... + 179621.

It is an arithmetic number, because the mean of its divisors is an integer number (40449240).

Almost surely, 2^643149621 is an apocalyptic number.

It is an amenable number.

643149621 is a deficient number, since it is larger than the sum of its proper divisors (327632139).

643149621 is a wasteful number, since it uses less digits than its factorization.

643149621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4505 (or 4502 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 643149621 is about 25360.3947327324. The cubic root of 643149621 is about 863.1852409513.

The spelling of 643149621 in words is "six hundred forty-three million, one hundred forty-nine thousand, six hundred twenty-one".