6636215981 has 4 divisors (see below), whose sum is σ = 6669564000. Its totient is φ = 6602867964.

The previous prime is 6636215941. The next prime is 6636216011. The reversal of 6636215981 is 1895126366.

It is a happy number.

6636215981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 6636215981 - 2⁶ = 6636215917 is a prime.

It is a super-2 number, since 2×6636215981² = 88078725092959584722, 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 (6636215941) 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, 16673711 + ... + 16674108.

It is an arithmetic number, because the mean of its divisors is an integer number (1667391000).

Almost surely, 2^6636215981 is an apocalyptic number.

It is an amenable number.

6636215981 is a deficient number, since it is larger than the sum of its proper divisors (33348019).

6636215981 is a wasteful number, since it uses less digits than its factorization.

6636215981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33348018.

The product of its digits is 466560, while the sum is 47.

The square root of 6636215981 is about 81462.9730675231. The cubic root of 6636215981 is about 1879.2021645743.

The spelling of 6636215981 in words is "six billion, six hundred thirty-six million, two hundred fifteen thousand, nine hundred eighty-one".