16645279421 has 2 divisors, whose sum is σ = 16645279422. Its totient is φ = 16645279420.

The previous prime is 16645279373. The next prime is 16645279451. The reversal of 16645279421 is 12497254661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16483735321 + 161544100 = 128389^2 + 12710^2 .

It is an emirp because it is prime and its reverse (12497254661) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16645279421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16645279451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8322639710 + 8322639711.

It is an arithmetic number, because the mean of its divisors is an integer number (8322639711).

Almost surely, 2^16645279421 is an apocalyptic number.

It is an amenable number.

16645279421 is a deficient number, since it is larger than the sum of its proper divisors (1).

16645279421 is an equidigital number, since it uses as much as digits as its factorization.

16645279421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725760, while the sum is 47.

The spelling of 16645279421 in words is "sixteen billion, six hundred forty-five million, two hundred seventy-nine thousand, four hundred twenty-one".