6624947981 has 4 divisors (see below), whose sum is σ = 6663242652. Its totient is φ = 6586653312.

The previous prime is 6624947971. The next prime is 6624947983. The reversal of 6624947981 is 1897494266.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6204082756 + 420865225 = 78766^2 + 20515^2 .

It is a cyclic number.

It is not a de Polignac number, because 6624947981 - 2¹⁴ = 6624931597 is a prime.

It is a super-2 number, since 2×6624947981² = 87779871501911952722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6624947983) 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, 19147076 + ... + 19147421.

It is an arithmetic number, because the mean of its divisors is an integer number (1665810663).

Almost surely, 2^6624947981 is an apocalyptic number.

It is an amenable number.

6624947981 is a deficient number, since it is larger than the sum of its proper divisors (38294671).

6624947981 is a wasteful number, since it uses less digits than its factorization.

6624947981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38294670.

The product of its digits is 5225472, while the sum is 56.

The square root of 6624947981 is about 81393.7834296944. The cubic root of 6624947981 is about 1878.1379614190.

The spelling of 6624947981 in words is "six billion, six hundred twenty-four million, nine hundred forty-seven thousand, nine hundred eighty-one".