16181272621 has 2 divisors, whose sum is σ = 16181272622. Its totient is φ = 16181272620.

The previous prime is 16181272619. The next prime is 16181272631. The reversal of 16181272621 is 12627218161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13044152521 + 3137120100 = 114211^2 + 56010^2 .

It is a cyclic number.

It is not a de Polignac number, because 16181272621 - 2¹ = 16181272619 is a prime.

Together with 16181272619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16181272631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8090636310 + 8090636311.

It is an arithmetic number, because the mean of its divisors is an integer number (8090636311).

Almost surely, 2^16181272621 is an apocalyptic number.

It is an amenable number.

16181272621 is a deficient number, since it is larger than the sum of its proper divisors (1).

16181272621 is an equidigital number, since it uses as much as digits as its factorization.

16181272621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 37.

The spelling of 16181272621 in words is "sixteen billion, one hundred eighty-one million, two hundred seventy-two thousand, six hundred twenty-one".