21151051556 has 12 divisors (see below), whose sum is σ = 37016973168. Its totient is φ = 10574773512.

The previous prime is 21151051549. The next prime is 21151051627. The reversal of 21151051556 is 65515015112.

It is a super-2 number, since 2×21151051556² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122246 + ... + 239261.

It is an arithmetic number, because the mean of its divisors is an integer number (3084747764).

Almost surely, 2^21151051556 is an apocalyptic number.

It is an amenable number.

21151051556 is a deficient number, since it is larger than the sum of its proper divisors (15865921612).

21151051556 is a wasteful number, since it uses less digits than its factorization.

21151051556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376138 (or 376136 counting only the distinct ones).

The product of its (nonzero) digits is 7500, while the sum is 32.

Adding to 21151051556 its reverse (65515015112), we get a palindrome (86666066668).

The spelling of 21151051556 in words is "twenty-one billion, one hundred fifty-one million, fifty-one thousand, five hundred fifty-six".