21125151844 has 6 divisors (see below), whose sum is σ = 36969015734. Its totient is φ = 10562575920.

The previous prime is 21125151823. The next prime is 21125151857. The reversal of 21125151844 is 44815152112.

It can be written as a sum of positive squares in only one way, i.e., 20999487744 + 125664100 = 144912^2 + 11210^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2640643977 + ... + 2640643984.

Almost surely, 2^21125151844 is an apocalyptic number.

It is an amenable number.

21125151844 is a deficient number, since it is larger than the sum of its proper divisors (15843863890).

21125151844 is a wasteful number, since it uses less digits than its factorization.

21125151844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5281287965 (or 5281287963 counting only the distinct ones).

The product of its digits is 12800, while the sum is 34.

The spelling of 21125151844 in words is "twenty-one billion, one hundred twenty-five million, one hundred fifty-one thousand, eight hundred forty-four".