66905549 has 4 divisors (see below), whose sum is σ = 68461536. Its totient is φ = 65349564.

The previous prime is 66905537. The next prime is 66905567. The reversal of 66905549 is 94550966.

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, and also an emirpimes, since its reverse is a distinct semiprime: 94550966 = 2 ⋅47275483.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66905549 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66905519) 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, 777929 + ... + 778014.

It is an arithmetic number, because the mean of its divisors is an integer number (17115384).

Almost surely, 2^66905549 is an apocalyptic number.

It is an amenable number.

66905549 is a deficient number, since it is larger than the sum of its proper divisors (1555987).

66905549 is a wasteful number, since it uses less digits than its factorization.

66905549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1555986.

The product of its (nonzero) digits is 291600, while the sum is 44.

The square root of 66905549 is about 8179.5812239992. The cubic root of 66905549 is about 405.9638659228.

The spelling of 66905549 in words is "sixty-six million, nine hundred five thousand, five hundred forty-nine".