21240136597 has 2 divisors, whose sum is σ = 21240136598. Its totient is φ = 21240136596.

The previous prime is 21240136591. The next prime is 21240136661. The reversal of 21240136597 is 79563104212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16765329361 + 4474807236 = 129481^2 + 66894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21240136597 - 2¹⁹ = 21239612309 is a prime.

It is a super-2 number, since 2×21240136597² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21240136591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620068298 + 10620068299.

It is an arithmetic number, because the mean of its divisors is an integer number (10620068299).

Almost surely, 2^21240136597 is an apocalyptic number.

It is an amenable number.

21240136597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240136597 is an equidigital number, since it uses as much as digits as its factorization.

21240136597 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 90720, while the sum is 40.

The spelling of 21240136597 in words is "twenty-one billion, two hundred forty million, one hundred thirty-six thousand, five hundred ninety-seven".