66356021 has 4 divisors (see below), whose sum is σ = 66437472. Its totient is φ = 66274572.

The previous prime is 66356011. The next prime is 66356029. The reversal of 66356021 is 12065366.

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 a cyclic number.

It is not a de Polignac number, because 66356021 - 2⁶ = 66355957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66356029) 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, 39491 + ... + 41136.

It is an arithmetic number, because the mean of its divisors is an integer number (16609368).

Almost surely, 2^66356021 is an apocalyptic number.

It is an amenable number.

66356021 is a deficient number, since it is larger than the sum of its proper divisors (81451).

66356021 is an equidigital number, since it uses as much as digits as its factorization.

66356021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81450.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 66356021 is about 8145.9205127475. The cubic root of 66356021 is about 404.8493490385.

The spelling of 66356021 in words is "sixty-six million, three hundred fifty-six thousand, twenty-one".