66420521 has 8 divisors (see below), whose sum is σ = 67965888. Its totient is φ = 64890000.

The previous prime is 66420503. The next prime is 66420539. The reversal of 66420521 is 12502466.

It is an interprime number because it is at equal distance from previous prime (66420503) and next prime (66420539).

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

It is a cyclic number.

It is not a de Polignac number, because 66420521 - 2¹⁸ = 66158377 is a prime.

It is a super-2 number, since 2×66420521² = 8823371219822882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66420421) 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, 5606 + ... + 12816.

It is an arithmetic number, because the mean of its divisors is an integer number (8495736).

Almost surely, 2^66420521 is an apocalyptic number.

66420521 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

66420521 is a deficient number, since it is larger than the sum of its proper divisors (1545367).

66420521 is a wasteful number, since it uses less digits than its factorization.

66420521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7423.

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 66420521 is about 8149.8785880527. The cubic root of 66420521 is about 404.9804817094.

Adding to 66420521 its reverse (12502466), we get a palindrome (78922987).

The spelling of 66420521 in words is "sixty-six million, four hundred twenty thousand, five hundred twenty-one".