21162506905 has 8 divisors (see below), whose sum is σ = 26014398984. Its totient is φ = 16517078400.

The previous prime is 21162506891. The next prime is 21162506909. The reversal of 21162506905 is 50960526112.

It can be written as a sum of positive squares in 4 ways, for example, as 66977856 + 21095529049 = 8184^2 + 145243^2 .

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

It is not a de Polignac number, because 21162506905 - 2²⁵ = 21128952473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21162506909) 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, 51615666 + ... + 51616075.

It is an arithmetic number, because the mean of its divisors is an integer number (3251799873).

Almost surely, 2^21162506905 is an apocalyptic number.

It is an amenable number.

21162506905 is a deficient number, since it is larger than the sum of its proper divisors (4851892079).

21162506905 is a wasteful number, since it uses less digits than its factorization.

21162506905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103231787.

The product of its (nonzero) digits is 32400, while the sum is 37.

The spelling of 21162506905 in words is "twenty-one billion, one hundred sixty-two million, five hundred six thousand, nine hundred five".