66215431 has 2 divisors, whose sum is σ = 66215432. Its totient is φ = 66215430.

The previous prime is 66215419. The next prime is 66215441. The reversal of 66215431 is 13451266.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66215431 is a prime.

It is a super-2 number, since 2×66215431² = 8768966605031522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 66215431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66215441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33107715 + 33107716.

It is an arithmetic number, because the mean of its divisors is an integer number (33107716).

Almost surely, 2^66215431 is an apocalyptic number.

66215431 is a deficient number, since it is larger than the sum of its proper divisors (1).

66215431 is an equidigital number, since it uses as much as digits as its factorization.

66215431 is an odious number, because the sum of its binary digits is odd.

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

The square root of 66215431 is about 8137.2864641722. The cubic root of 66215431 is about 404.5632257189.

Adding to 66215431 its reverse (13451266), we get a palindrome (79666697).

The spelling of 66215431 in words is "sixty-six million, two hundred fifteen thousand, four hundred thirty-one".