66351631 has 4 divisors (see below), whose sum is σ = 66858264. Its totient is φ = 65845000.

The previous prime is 66351569. The next prime is 66351683. The reversal of 66351631 is 13615366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13615366 = 2 ⋅6807683.

It is a cyclic number.

It is not a de Polignac number, because 66351631 - 2⁷ = 66351503 is a prime.

It is a super-2 number, since 2×66351631² = 8805077872720322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66351593 and 66351602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66351431) 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, 253120 + ... + 253381.

It is an arithmetic number, because the mean of its divisors is an integer number (16714566).

Almost surely, 2^66351631 is an apocalyptic number.

66351631 is a deficient number, since it is larger than the sum of its proper divisors (506633).

66351631 is a wasteful number, since it uses less digits than its factorization.

66351631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506632.

The product of its digits is 9720, while the sum is 31.

The square root of 66351631 is about 8145.6510482588. The cubic root of 66351631 is about 404.8404207965.

Adding to 66351631 its reverse (13615366), we get a palindrome (79966997).

The spelling of 66351631 in words is "sixty-six million, three hundred fifty-one thousand, six hundred thirty-one".