21406213065 has 8 divisors (see below), whose sum is σ = 34249940928. Its totient is φ = 11416646960.

The previous prime is 21406213057. The next prime is 21406213069. The reversal of 21406213065 is 56031260412.

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

It is not a de Polignac number, because 21406213065 - 2³ = 21406213057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21406213069) 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, 713540421 + ... + 713540450.

It is an arithmetic number, because the mean of its divisors is an integer number (4281242616).

Almost surely, 2^21406213065 is an apocalyptic number.

It is an amenable number.

21406213065 is a deficient number, since it is larger than the sum of its proper divisors (12843727863).

21406213065 is a wasteful number, since it uses less digits than its factorization.

21406213065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1427080879.

The product of its (nonzero) digits is 8640, while the sum is 30.

Adding to 21406213065 its reverse (56031260412), we get a palindrome (77437473477).

The spelling of 21406213065 in words is "twenty-one billion, four hundred six million, two hundred thirteen thousand, sixty-five".