21095121956 has 12 divisors (see below), whose sum is σ = 36952627740. Its totient is φ = 10537228320.

The previous prime is 21095121953. The next prime is 21095121973. The reversal of 21095121956 is 65912159012.

It can be written as a sum of positive squares in 2 ways, for example, as 12863189056 + 8231932900 = 113416^2 + 90730^2 .

It is not an unprimeable number, because it can be changed into a prime (21095121953) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2578571 + ... + 2586738.

It is an arithmetic number, because the mean of its divisors is an integer number (3079385645).

Almost surely, 2^21095121956 is an apocalyptic number.

It is an amenable number.

21095121956 is a deficient number, since it is larger than the sum of its proper divisors (15857505784).

21095121956 is a wasteful number, since it uses less digits than its factorization.

21095121956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5166334 (or 5166332 counting only the distinct ones).

The product of its (nonzero) digits is 48600, while the sum is 41.

The spelling of 21095121956 in words is "twenty-one billion, ninety-five million, one hundred twenty-one thousand, nine hundred fifty-six".