21197239529 has 2 divisors, whose sum is σ = 21197239530. Its totient is φ = 21197239528.

The previous prime is 21197239493. The next prime is 21197239577. The reversal of 21197239529 is 92593279112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18052609600 + 3144629929 = 134360^2 + 56077^2 .

It is a cyclic number.

It is not a de Polignac number, because 21197239529 - 2¹⁶ = 21197173993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21197233529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10598619764 + 10598619765.

It is an arithmetic number, because the mean of its divisors is an integer number (10598619765).

Almost surely, 2^21197239529 is an apocalyptic number.

It is an amenable number.

21197239529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21197239529 is an equidigital number, since it uses as much as digits as its factorization.

21197239529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 612360, while the sum is 50.

The spelling of 21197239529 in words is "twenty-one billion, one hundred ninety-seven million, two hundred thirty-nine thousand, five hundred twenty-nine".