66561371 has 8 divisors (see below), whose sum is σ = 69580800. Its totient is φ = 63596520.

The previous prime is 66561359. The next prime is 66561373. The reversal of 66561371 is 17316566.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66561371 is a prime.

It is a super-2 number, since 2×66561371² = 8860832218799282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66561373) 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, 11141 + ... + 16038.

It is an arithmetic number, because the mean of its divisors is an integer number (8697600).

Almost surely, 2^66561371 is an apocalyptic number.

66561371 is a deficient number, since it is larger than the sum of its proper divisors (3019429).

66561371 is a wasteful number, since it uses less digits than its factorization.

66561371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27289.

The product of its digits is 22680, while the sum is 35.

The square root of 66561371 is about 8158.5152448224. The cubic root of 66561371 is about 405.2665440441.

The spelling of 66561371 in words is "sixty-six million, five hundred sixty-one thousand, three hundred seventy-one".