21154067065 has 16 divisors (see below), whose sum is σ = 25497287568. Its totient is φ = 16848388096.

The previous prime is 21154067057. The next prime is 21154067071. The reversal of 21154067065 is 56076045112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 1201939561 + 19952127504 = 34669^2 + 141252^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154067065 - 2³ = 21154067057 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3457449 + ... + 3463561.

It is an arithmetic number, because the mean of its divisors is an integer number (1593580473).

Almost surely, 2^21154067065 is an apocalyptic number.

It is an amenable number.

21154067065 is a deficient number, since it is larger than the sum of its proper divisors (4343220503).

21154067065 is a wasteful number, since it uses less digits than its factorization.

21154067065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9068.

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21154067065 in words is "twenty-one billion, one hundred fifty-four million, sixty-seven thousand, sixty-five".