21443209225 has 9 divisors (see below), whose sum is σ = 26590487367. Its totient is φ = 17153981640.

The previous prime is 21443209211. The next prime is 21443209273. The reversal of 21443209225 is 52290234412.

The square root of 21443209225 is 146435.

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., 7719555321 + 13723653904 = 87861^2 + 117148^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21443209225 is a prime.

It is a super-2 number, since 2×21443209225² (a number of 21 digits) contains 22 as substring.

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 8 ways as a sum of consecutive naturals, for example, 717532 + ... + 746818.

Almost surely, 2^21443209225 is an apocalyptic number.

21443209225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21443209225 is the 146435-th square number.

21443209225 is the 73218-th centered octagonal number.

It is an amenable number.

21443209225 is a deficient number, since it is larger than the sum of its proper divisors (5147278142).

21443209225 is an frugal number, since it uses more digits than its factorization.

21443209225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58584 (or 29292 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The spelling of 21443209225 in words is "twenty-one billion, four hundred forty-three million, two hundred nine thousand, two hundred twenty-five".