66905390 has 32 divisors (see below), whose sum is σ = 126406656. Its totient is φ = 25447840.

The previous prime is 66905381. The next prime is 66905429. The reversal of 66905390 is 9350966.

It is a super-4 number, since 4×66905390⁴ (a number of 32 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3, 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43169 + ... + 44691.

It is an arithmetic number, because the mean of its divisors is an integer number (3950208).

Almost surely, 2^66905390 is an apocalyptic number.

66905390 is a deficient number, since it is larger than the sum of its proper divisors (59501266).

66905390 is a wasteful number, since it uses less digits than its factorization.

66905390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1744.

The product of its (nonzero) digits is 43740, while the sum is 38.

The square root of 66905390 is about 8179.5715046694. The cubic root of 66905390 is about 405.9635443336.

The spelling of 66905390 in words is "sixty-six million, nine hundred five thousand, three hundred ninety".