21554644225 has 9 divisors (see below), whose sum is σ = 26728669123. Its totient is φ = 17243128120.

The previous prime is 21554644213. The next prime is 21554644249. The reversal of 21554644225 is 52244645512.

The square root of 21554644225 is 146815.

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., 7759671921 + 13794972304 = 88089^2 + 117452^2 .

It is not a de Polignac number, because 21554644225 - 2¹¹ = 21554642177 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 719394 + ... + 748756.

Almost surely, 2^21554644225 is an apocalyptic number.

21554644225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21554644225 is the 146815-th square number.

21554644225 is the 73408-th centered octagonal number.

It is an amenable number.

21554644225 is a deficient number, since it is larger than the sum of its proper divisors (5174024898).

21554644225 is an frugal number, since it uses more digits than its factorization.

21554644225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58736 (or 29368 counting only the distinct ones).

The product of its digits is 384000, while the sum is 40.

The spelling of 21554644225 in words is "twenty-one billion, five hundred fifty-four million, six hundred forty-four thousand, two hundred twenty-five".