20517666 has 16 divisors (see below), whose sum is σ = 44192064. Its totient is φ = 6313104.

The previous prime is 20517661. The next prime is 20517677. The reversal of 20517666 is 66671502.

It is not an unprimeable number, because it can be changed into a prime (20517661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131446 + ... + 131601.

It is an arithmetic number, because the mean of its divisors is an integer number (2762004).

Almost surely, 2^20517666 is an apocalyptic number.

20517666 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

20517666 is an abundant number, since it is smaller than the sum of its proper divisors (23674398).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20517666 is a wasteful number, since it uses less digits than its factorization.

20517666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263065.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 20517666 is about 4529.6430322929. The cubic root of 20517666 is about 273.7637777932.

It can be divided in two parts, 205 and 17666, that added together give a palindrome (17871).

The spelling of 20517666 in words is "twenty million, five hundred seventeen thousand, six hundred sixty-six".