66899957 has 4 divisors (see below), whose sum is σ = 67349100. Its totient is φ = 66450816.

The previous prime is 66899951. The next prime is 66899983. The reversal of 66899957 is 75999866.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14032516 + 52867441 = 3746^2 + 7271^2 .

It is a cyclic number.

It is not a de Polignac number, because 66899957 - 2²⁰ = 65851381 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66899896 and 66899905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66899951) 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, 224348 + ... + 224645.

It is an arithmetic number, because the mean of its divisors is an integer number (16837275).

Almost surely, 2^66899957 is an apocalyptic number.

It is an amenable number.

66899957 is a deficient number, since it is larger than the sum of its proper divisors (449143).

66899957 is a wasteful number, since it uses less digits than its factorization.

66899957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449142.

The product of its digits is 7348320, while the sum is 59.

The square root of 66899957 is about 8179.2393900656. The cubic root of 66899957 is about 405.9525553851.

Subtracting 66899957 from its reverse (75999866), we obtain a palindrome (9099909).

The spelling of 66899957 in words is "sixty-six million, eight hundred ninety-nine thousand, nine hundred fifty-seven".