66819291 has 72 divisors (see below), whose sum is σ = 119541312. Its totient is φ = 32810400.

The previous prime is 66819287. The next prime is 66819317. The reversal of 66819291 is 19291866.

It is not a de Polignac number, because 66819291 - 2² = 66819287 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66819251) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1553916 + ... + 1553958.

It is an arithmetic number, because the mean of its divisors is an integer number (1660296).

Almost surely, 2^66819291 is an apocalyptic number.

66819291 is a deficient number, since it is larger than the sum of its proper divisors (52722021).

66819291 is a wasteful number, since it uses less digits than its factorization.

66819291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 95 counting only the distinct ones).

The product of its digits is 46656, while the sum is 42.

The square root of 66819291 is about 8174.3067595974. The cubic root of 66819291 is about 405.7893278798.

The spelling of 66819291 in words is "sixty-six million, eight hundred nineteen thousand, two hundred ninety-one".