21211665231109 has 2 divisors, whose sum is σ = 21211665231110. Its totient is φ = 21211665231108.

The previous prime is 21211665231077. The next prime is 21211665231157. The reversal of 21211665231109 is 90113256611212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18466357562500 + 2745307668609 = 4297250^2 + 1656897^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211665231109 - 2⁵ = 21211665231077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211665231209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605832615554 + 10605832615555.

It is an arithmetic number, because the mean of its divisors is an integer number (10605832615555).

Almost surely, 2^{21211665231109} is an apocalyptic number.

It is an amenable number.

21211665231109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211665231109 is an equidigital number, since it uses as much as digits as its factorization.

21211665231109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 40.

The spelling of 21211665231109 in words is "twenty-one trillion, two hundred eleven billion, six hundred sixty-five million, two hundred thirty-one thousand, one hundred nine".