16181972154521 has 2 divisors, whose sum is σ = 16181972154522. Its totient is φ = 16181972154520.

The previous prime is 16181972154433. The next prime is 16181972154547. The reversal of 16181972154521 is 12545127918161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14854580138896 + 1327392015625 = 3854164^2 + 1152125^2 .

It is a cyclic number.

It is not a de Polignac number, because 16181972154521 - 2¹⁰ = 16181972153497 is a prime.

It is not a weakly prime, because it can be changed into another prime (16181972154571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8090986077260 + 8090986077261.

It is an arithmetic number, because the mean of its divisors is an integer number (8090986077261).

Almost surely, 2^{16181972154521} is an apocalyptic number.

It is an amenable number.

16181972154521 is a deficient number, since it is larger than the sum of its proper divisors (1).

16181972154521 is an equidigital number, since it uses as much as digits as its factorization.

16181972154521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1209600, while the sum is 53.

The spelling of 16181972154521 in words is "sixteen trillion, one hundred eighty-one billion, nine hundred seventy-two million, one hundred fifty-four thousand, five hundred twenty-one".