21196739281 has 27 divisors (see below), whose sum is σ = 22479448593. Its totient is φ = 19986732480.

The previous prime is 21196739237. The next prime is 21196739287. The reversal of 21196739281 is 18293769112.

It is a happy number.

The square root of 21196739281 is 145591.

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

It can be written as a sum of positive squares in 4 ways, for example, as 2294889025 + 18901850256 = 47905^2 + 137484^2 .

It is not a de Polignac number, because 21196739281 - 2⁹ = 21196738769 is a prime.

It is a super-2 number, since 2×21196739281² (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 (21196739287) by changing a digit.

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 26 ways as a sum of consecutive naturals, for example, 316369210 + ... + 316369276.

Almost surely, 2^21196739281 is an apocalyptic number.

21196739281 is the 145591-st square number.

21196739281 is the 72796-th centered octagonal number.

It is an amenable number.

21196739281 is a deficient number, since it is larger than the sum of its proper divisors (1282709312).

21196739281 is an frugal number, since it uses more digits than its factorization.

21196739281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322 (or 161 counting only the distinct ones).

The product of its digits is 326592, while the sum is 49.

Multiplying 21196739281 by its sum of digits (49), we get a square (1038640224769 = 1019137²).

The spelling of 21196739281 in words is "twenty-one billion, one hundred ninety-six million, seven hundred thirty-nine thousand, two hundred eighty-one".