21154431415 has 16 divisors (see below), whose sum is σ = 27801396000. Its totient is φ = 15356956032.

The previous prime is 21154431407. The next prime is 21154431479. The reversal of 21154431415 is 51413445112.

It is a cyclic number.

It is not a de Polignac number, because 21154431415 - 2³ = 21154431407 is a prime.

It is a congruent 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, 2754240 + ... + 2761909.

It is an arithmetic number, because the mean of its divisors is an integer number (1737587250).

Almost surely, 2^21154431415 is an apocalyptic number.

21154431415 is a deficient number, since it is larger than the sum of its proper divisors (6646964585).

21154431415 is a wasteful number, since it uses less digits than its factorization.

21154431415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5516226.

The product of its digits is 9600, while the sum is 31.

Adding to 21154431415 its reverse (51413445112), we get a palindrome (72567876527).

The spelling of 21154431415 in words is "twenty-one billion, one hundred fifty-four million, four hundred thirty-one thousand, four hundred fifteen".