21267555556 has 81 divisors (see below), whose sum is σ = 41400988713. Its totient is φ = 9555043680.

The previous prime is 21267555527. The next prime is 21267555587. The reversal of 21267555556 is 65555576212.

The square root of 21267555556 is 145834.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 3146088100 + 18121467456 = 56090^2 + 134616^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 269209525 + ... + 269209603.

Almost surely, 2^21267555556 is an apocalyptic number.

21267555556 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21267555556 is the 145834-th square number.

It is an amenable number.

21267555556 is a deficient number, since it is larger than the sum of its proper divisors (20133433157).

21267555556 is an equidigital number, since it uses as much as digits as its factorization.

21267555556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330 (or 165 counting only the distinct ones).

The product of its digits is 3150000, while the sum is 49.

Multiplying 21267555556 by its sum of digits (49), we get a square (1042110222244 = 1020838²).

The spelling of 21267555556 in words is "twenty-one billion, two hundred sixty-seven million, five hundred fifty-five thousand, five hundred fifty-six".