66421531 has 4 divisors (see below), whose sum is σ = 72459864. Its totient is φ = 60383200.

The previous prime is 66421489. The next prime is 66421547. The reversal of 66421531 is 13512466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66421531 - 2⁷ = 66421403 is a prime.

It is a super-2 number, since 2×66421531² = 8823639560767922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66421531.

It is not an unprimeable number, because it can be changed into a prime (66421231) 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, 3019150 + ... + 3019171.

It is an arithmetic number, because the mean of its divisors is an integer number (18114966).

Almost surely, 2^66421531 is an apocalyptic number.

66421531 is a deficient number, since it is larger than the sum of its proper divisors (6038333).

66421531 is a wasteful number, since it uses less digits than its factorization.

66421531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6038332.

The product of its digits is 4320, while the sum is 28.

The square root of 66421531 is about 8149.9405519304. The cubic root of 66421531 is about 404.9825344295.

Adding to 66421531 its reverse (13512466), we get a palindrome (79933997).

The spelling of 66421531 in words is "sixty-six million, four hundred twenty-one thousand, five hundred thirty-one".