21522943849 has 9 divisors (see below), whose sum is σ = 23659224631. Its totient is φ = 19564845520.

The previous prime is 21522943837. The next prime is 21522943859. The reversal of 21522943849 is 94834922512.

The square root of 21522943849 is 146707.

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., 6039621225 + 15483322624 = 77715^2 + 124432^2 .

It is not a de Polignac number, because 21522943849 - 2⁵ = 21522943817 is a prime.

It is a super-2 number, since 2×21522943849² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21522943829) by changing a digit.

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, 1607109 + ... + 1620445.

Almost surely, 2^21522943849 is an apocalyptic number.

21522943849 is the 146707-th square number.

21522943849 is the 73354-th centered octagonal number.

It is an amenable number.

21522943849 is a deficient number, since it is larger than the sum of its proper divisors (2136280782).

21522943849 is an frugal number, since it uses more digits than its factorization.

21522943849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26696 (or 13348 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 49.

Multiplying 21522943849 by its sum of digits (49), we get a square (1054624248601 = 1026949²).

The spelling of 21522943849 in words is "twenty-one billion, five hundred twenty-two million, nine hundred forty-three thousand, eight hundred forty-nine".