6643061987 has 4 divisors (see below), whose sum is σ = 6872133120. Its totient is φ = 6413990856.

The previous prime is 6643061981. The next prime is 6643062011. The reversal of 6643061987 is 7891603466.

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

It is a cyclic number.

It is not a de Polignac number, because 6643061987 - 2¹² = 6643057891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6643061981) 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, 114535523 + ... + 114535580.

It is an arithmetic number, because the mean of its divisors is an integer number (1718033280).

Almost surely, 2^6643061987 is an apocalyptic number.

6643061987 is a deficient number, since it is larger than the sum of its proper divisors (229071133).

6643061987 is a wasteful number, since it uses less digits than its factorization.

6643061987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229071132.

The product of its (nonzero) digits is 1306368, while the sum is 50.

The square root of 6643061987 is about 81504.9813631044. The cubic root of 6643061987 is about 1879.8481455548.

The spelling of 6643061987 in words is "six billion, six hundred forty-three million, sixty-one thousand, nine hundred eighty-seven".