18024720421 has 2 divisors, whose sum is σ = 18024720422. Its totient is φ = 18024720420.

The previous prime is 18024720419. The next prime is 18024720449. The reversal of 18024720421 is 12402742081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13638969796 + 4385750625 = 116786^2 + 66225^2 .

It is a cyclic number.

It is not a de Polignac number, because 18024720421 - 2¹ = 18024720419 is a prime.

Together with 18024720419, 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 (18024720401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9012360210 + 9012360211.

It is an arithmetic number, because the mean of its divisors is an integer number (9012360211).

Almost surely, 2^18024720421 is an apocalyptic number.

It is an amenable number.

18024720421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18024720421 is an equidigital number, since it uses as much as digits as its factorization.

18024720421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7168, while the sum is 31.

The spelling of 18024720421 in words is "eighteen billion, twenty-four million, seven hundred twenty thousand, four hundred twenty-one".