66621081 has 4 divisors (see below), whose sum is σ = 88828112. Its totient is φ = 44414052.

The previous prime is 66621017. The next prime is 66621083. The reversal of 66621081 is 18012666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66621081 - 2⁶ = 66621017 is a prime.

It is a super-2 number, since 2×66621081² = 8876736867217122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66621083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11103511 + ... + 11103516.

It is an arithmetic number, because the mean of its divisors is an integer number (22207028).

Almost surely, 2^66621081 is an apocalyptic number.

It is an amenable number.

66621081 is a deficient number, since it is larger than the sum of its proper divisors (22207031).

66621081 is a wasteful number, since it uses less digits than its factorization.

66621081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22207030.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 66621081 is about 8162.1737913377. The cubic root of 66621081 is about 405.3876915541.

The spelling of 66621081 in words is "sixty-six million, six hundred twenty-one thousand, eighty-one".