21155103124 has 6 divisors (see below), whose sum is σ = 37021430474. Its totient is φ = 10577551560.

The previous prime is 21155103113. The next prime is 21155103143. The reversal of 21155103124 is 42130155112.

It can be written as a sum of positive squares in only one way, i.e., 17021899024 + 4133204100 = 130468^2 + 64290^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2644387887 + ... + 2644387894.

Almost surely, 2^21155103124 is an apocalyptic number.

It is an amenable number.

21155103124 is a deficient number, since it is larger than the sum of its proper divisors (15866327350).

21155103124 is a wasteful number, since it uses less digits than its factorization.

21155103124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5288775785 (or 5288775783 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 25.

Adding to 21155103124 its reverse (42130155112), we get a palindrome (63285258236).

The spelling of 21155103124 in words is "twenty-one billion, one hundred fifty-five million, one hundred three thousand, one hundred twenty-four".