21956274537497 has 2 divisors, whose sum is σ = 21956274537498. Its totient is φ = 21956274537496.

The previous prime is 21956274537487. The next prime is 21956274537503. The reversal of 21956274537497 is 79473547265912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11053889418121 + 10902385119376 = 3324739^2 + 3301876^2 .

It is a cyclic number.

It is not a de Polignac number, because 21956274537497 - 2¹⁶ = 21956274471961 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21956274537497.

It is not a weakly prime, because it can be changed into another prime (21956274537427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978137268748 + 10978137268749.

It is an arithmetic number, because the mean of its divisors is an integer number (10978137268749).

Almost surely, 2^{21956274537497} is an apocalyptic number.

It is an amenable number.

21956274537497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956274537497 is an equidigital number, since it uses as much as digits as its factorization.

21956274537497 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 800150400, while the sum is 71.

The spelling of 21956274537497 in words is "twenty-one trillion, nine hundred fifty-six billion, two hundred seventy-four million, five hundred thirty-seven thousand, four hundred ninety-seven".