21697744177 has 2 divisors, whose sum is σ = 21697744178. Its totient is φ = 21697744176.

The previous prime is 21697744091. The next prime is 21697744183. The reversal of 21697744177 is 77144779612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21468403441 + 229340736 = 146521^2 + 15144^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21697744177 is a prime.

It is not a weakly prime, because it can be changed into another prime (21697747177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10848872088 + 10848872089.

It is an arithmetic number, because the mean of its divisors is an integer number (10848872089).

Almost surely, 2^21697744177 is an apocalyptic number.

It is an amenable number.

21697744177 is a deficient number, since it is larger than the sum of its proper divisors (1).

21697744177 is an equidigital number, since it uses as much as digits as its factorization.

21697744177 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4148928, while the sum is 55.

The spelling of 21697744177 in words is "twenty-one billion, six hundred ninety-seven million, seven hundred forty-four thousand, one hundred seventy-seven".