21312311161 has 2 divisors, whose sum is σ = 21312311162. Its totient is φ = 21312311160.

The previous prime is 21312311123. The next prime is 21312311177. The reversal of 21312311161 is 16111321312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12980272761 + 8332038400 = 113931^2 + 91280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312311161 - 2¹³ = 21312302969 is a prime.

It is not a weakly prime, because it can be changed into another prime (21312311261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656155580 + 10656155581.

It is an arithmetic number, because the mean of its divisors is an integer number (10656155581).

Almost surely, 2^21312311161 is an apocalyptic number.

It is an amenable number.

21312311161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312311161 is an equidigital number, since it uses as much as digits as its factorization.

21312311161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216, while the sum is 22.

Adding to 21312311161 its reverse (16111321312), we get a palindrome (37423632473).

The spelling of 21312311161 in words is "twenty-one billion, three hundred twelve million, three hundred eleven thousand, one hundred sixty-one".