21661465732369 has 2 divisors, whose sum is σ = 21661465732370. Its totient is φ = 21661465732368.

The previous prime is 21661465732331. The next prime is 21661465732391. The reversal of 21661465732369 is 96323756416612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21655015715025 + 6450017344 = 4653495^2 + 80312^2 .

It is a cyclic number.

It is not a de Polignac number, because 21661465732369 - 2²⁵ = 21661432177937 is a prime.

It is a super-2 number, since 2×21661465732369² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21661465735369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830732866184 + 10830732866185.

It is an arithmetic number, because the mean of its divisors is an integer number (10830732866185).

Almost surely, 2^{21661465732369} is an apocalyptic number.

It is an amenable number.

21661465732369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21661465732369 is an equidigital number, since it uses as much as digits as its factorization.

21661465732369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 58786560, while the sum is 61.

The spelling of 21661465732369 in words is "twenty-one trillion, six hundred sixty-one billion, four hundred sixty-five million, seven hundred thirty-two thousand, three hundred sixty-nine".