166238667421 has 2 divisors, whose sum is σ = 166238667422. Its totient is φ = 166238667420.

The previous prime is 166238667323. The next prime is 166238667437. The reversal of 166238667421 is 124766832661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 92179032100 + 74059635321 = 303610^2 + 272139^2 .

It is a cyclic number.

It is not a de Polignac number, because 166238667421 - 2¹³ = 166238659229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166238667481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83119333710 + 83119333711.

It is an arithmetic number, because the mean of its divisors is an integer number (83119333711).

Almost surely, 2^166238667421 is an apocalyptic number.

It is an amenable number.

166238667421 is a deficient number, since it is larger than the sum of its proper divisors (1).

166238667421 is an equidigital number, since it uses as much as digits as its factorization.

166238667421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648, while the sum is 52.

The spelling of 166238667421 in words is "one hundred sixty-six billion, two hundred thirty-eight million, six hundred sixty-seven thousand, four hundred twenty-one".