21518337097 has 2 divisors, whose sum is σ = 21518337098. Its totient is φ = 21518337096.

The previous prime is 21518337041. The next prime is 21518337101. The reversal of 21518337097 is 79073381512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21518249481 + 87616 = 146691^2 + 296^2 .

It is a cyclic number.

It is not a de Polignac number, because 21518337097 - 2¹⁵ = 21518304329 is a prime.

It is not a weakly prime, because it can be changed into another prime (21518337697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759168548 + 10759168549.

It is an arithmetic number, because the mean of its divisors is an integer number (10759168549).

Almost surely, 2^21518337097 is an apocalyptic number.

It is an amenable number.

21518337097 is a deficient number, since it is larger than the sum of its proper divisors (1).

21518337097 is an equidigital number, since it uses as much as digits as its factorization.

21518337097 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 317520, while the sum is 46.

The spelling of 21518337097 in words is "twenty-one billion, five hundred eighteen million, three hundred thirty-seven thousand, ninety-seven".