66020781 has 16 divisors (see below), whose sum is σ = 90478080. Its totient is φ = 42798000.

The previous prime is 66020761. The next prime is 66020789. The reversal of 66020781 is 18702066.

It is a happy number.

It is not a de Polignac number, because 66020781 - 2¹⁰ = 66019757 is a prime.

It is a super-2 number, since 2×66020781² = 8717487047699922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66020789) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31360 + ... + 33398.

It is an arithmetic number, because the mean of its divisors is an integer number (5654880).

Almost surely, 2^66020781 is an apocalyptic number.

It is an amenable number.

66020781 is a deficient number, since it is larger than the sum of its proper divisors (24457299).

66020781 is a wasteful number, since it uses less digits than its factorization.

66020781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2336.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 66020781 is about 8125.3172861126. The cubic root of 66020781 is about 404.1664122623.

The spelling of 66020781 in words is "sixty-six million, twenty thousand, seven hundred eighty-one".