664373641981 has 16 divisors (see below), whose sum is σ = 760300369920. Its totient is φ = 568701239040.

The previous prime is 664373641963. The next prime is 664373642003. The reversal of 664373641981 is 189146373466.

It is a cyclic number.

It is not a de Polignac number, because 664373641981 - 2¹⁵ = 664373609213 is a prime.

It is a super-2 number, since 2×664373641981² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664373641931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46165135 + ... + 46179523.

It is an arithmetic number, because the mean of its divisors is an integer number (47518773120).

Almost surely, 2^664373641981 is an apocalyptic number.

It is an amenable number.

664373641981 is a deficient number, since it is larger than the sum of its proper divisors (95926727939).

664373641981 is a wasteful number, since it uses less digits than its factorization.

664373641981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22764.

The product of its digits is 15676416, while the sum is 58.

The spelling of 664373641981 in words is "six hundred sixty-four billion, three hundred seventy-three million, six hundred forty-one thousand, nine hundred eighty-one".