19660821604 has 6 divisors (see below), whose sum is σ = 34406437814.
Its totient is φ = 9830410800.
The previous prime is 19660821601. The next prime is 19660821617. The reversal of 19660821604 is 40612806691.
It can be written as a sum of positive squares in only one way, i.e., 19622406400 + 38415204 = 140080^2 + 6198^2
It is a super-2 number, since 2×196608216042 (a number of 21 digits) contains 22 as substring.
It is not an unprimeable number, because it can be changed into a prime (19660821601) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2457602697 + ... + 2457602704.
Almost surely, 219660821604 is an apocalyptic number.
It is an amenable number.
19660821604 is a deficient number, since it is larger than the sum of its proper divisors (14745616210).
19660821604 is a wasteful number, since it uses less digits than its factorization.
19660821604 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 4915205405 (or 4915205403 counting only the distinct ones).
The product of its (nonzero) digits is 124416, while the sum is 43.
The spelling of 19660821604 in words is "nineteen billion, six hundred sixty million, eight hundred twenty-one thousand, six hundred four".