6645631 has 4 divisors (see below), whose sum is σ = 6651064. Its totient is φ = 6640200.

The previous prime is 6645619. The next prime is 6645637. The reversal of 6645631 is 1365466.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1365466 = 2 ⋅682733.

It is a cyclic number.

It is not a de Polignac number, because 6645631 - 2¹³ = 6637439 is a prime.

It is a super-2 number, since 2×6645631² = 88328822776322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6645593 and 6645602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6645637) 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, 76 + ... + 3646.

It is an arithmetic number, because the mean of its divisors is an integer number (1662766).

Almost surely, 2^6645631 is an apocalyptic number.

6645631 is a deficient number, since it is larger than the sum of its proper divisors (5433).

6645631 is a wasteful number, since it uses less digits than its factorization.

6645631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5432.

The product of its digits is 12960, while the sum is 31.

The square root of 6645631 is about 2577.9121396975. The cubic root of 6645631 is about 188.0090440043.

The spelling of 6645631 in words is "six million, six hundred forty-five thousand, six hundred thirty-one".