66121705 has 16 divisors (see below), whose sum is σ = 85942080. Its totient is φ = 48547008.

The previous prime is 66121681. The next prime is 66121733. The reversal of 66121705 is 50712166.

It is a cyclic number.

It is not a de Polignac number, because 66121705 - 2⁹ = 66121193 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8794 + ... + 14476.

It is an arithmetic number, because the mean of its divisors is an integer number (5371380).

Almost surely, 2^66121705 is an apocalyptic number.

66121705 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66121705 is a deficient number, since it is larger than the sum of its proper divisors (19820375).

66121705 is a wasteful number, since it uses less digits than its factorization.

66121705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5880.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 66121705 is about 8131.5253796566. The cubic root of 66121705 is about 404.3722531261.

It can be divided in two parts, 661 and 21705, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 66121705 in words is "sixty-six million, one hundred twenty-one thousand, seven hundred five".