66513208381 has 4 divisors (see below), whose sum is σ = 66515703264. Its totient is φ = 66510713500.

The previous prime is 66513208369. The next prime is 66513208403. The reversal of 66513208381 is 18380231566.

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 66513208381 - 2¹³ = 66513200189 is a prime.

It is a super-2 number, since 2×66513208381² (a number of 22 digits) 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 (66513208331) 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, 1207015 + ... + 1260916.

It is an arithmetic number, because the mean of its divisors is an integer number (16628925816).

Almost surely, 2^66513208381 is an apocalyptic number.

It is an amenable number.

66513208381 is a deficient number, since it is larger than the sum of its proper divisors (2494883).

66513208381 is a wasteful number, since it uses less digits than its factorization.

66513208381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2494882.

The product of its (nonzero) digits is 207360, while the sum is 43.

The spelling of 66513208381 in words is "sixty-six billion, five hundred thirteen million, two hundred eight thousand, three hundred eighty-one".