21131477618197 has 2 divisors, whose sum is σ = 21131477618198. Its totient is φ = 21131477618196.

The previous prime is 21131477618171. The next prime is 21131477618231. The reversal of 21131477618197 is 79181677413112.

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., 17224209842436 + 3907267775761 = 4150206^2 + 1976681^2 .

It is a cyclic number.

It is not a de Polignac number, because 21131477618197 - 2³⁹ = 20581721804309 is a prime.

It is a super-2 number, since 2×21131477618197² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131477618597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565738809098 + 10565738809099.

It is an arithmetic number, because the mean of its divisors is an integer number (10565738809099).

Almost surely, 2^{21131477618197} is an apocalyptic number.

It is an amenable number.

21131477618197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131477618197 is an equidigital number, since it uses as much as digits as its factorization.

21131477618197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3556224, while the sum is 58.

The spelling of 21131477618197 in words is "twenty-one trillion, one hundred thirty-one billion, four hundred seventy-seven million, six hundred eighteen thousand, one hundred ninety-seven".