21506065664467 has 2 divisors, whose sum is σ = 21506065664468. Its totient is φ = 21506065664466.

The previous prime is 21506065664453. The next prime is 21506065664471. The reversal of 21506065664467 is 76446656060512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21506065664467 is a prime.

It is not a weakly prime, because it can be changed into another prime (21506065664407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753032832233 + 10753032832234.

It is an arithmetic number, because the mean of its divisors is an integer number (10753032832234).

Almost surely, 2^{21506065664467} is an apocalyptic number.

21506065664467 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506065664467 is an equidigital number, since it uses as much as digits as its factorization.

21506065664467 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43545600, while the sum is 58.

The spelling of 21506065664467 in words is "twenty-one trillion, five hundred six billion, sixty-five million, six hundred sixty-four thousand, four hundred sixty-seven".