21315010505 has 16 divisors (see below), whose sum is σ = 26910034704. Its totient is φ = 16186475520.

The previous prime is 21315010489. The next prime is 21315010523. The reversal of 21315010505 is 50501051312.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 146797456 + 21168213049 = 12116^2 + 145493^2 .

It is not a de Polignac number, because 21315010505 - 2⁴ = 21315010489 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1397492 + ... + 1412661.

It is an arithmetic number, because the mean of its divisors is an integer number (1681877169).

Almost surely, 2^21315010505 is an apocalyptic number.

It is an amenable number.

21315010505 is a deficient number, since it is larger than the sum of its proper divisors (5595024199).

21315010505 is a wasteful number, since it uses less digits than its factorization.

21315010505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2810236.

The product of its (nonzero) digits is 750, while the sum is 23.

Adding to 21315010505 its reverse (50501051312), we get a palindrome (71816061817).

The spelling of 21315010505 in words is "twenty-one billion, three hundred fifteen million, ten thousand, five hundred five".