18700644421 has 2 divisors, whose sum is σ = 18700644422. Its totient is φ = 18700644420.

The previous prime is 18700644407. The next prime is 18700644437. The reversal of 18700644421 is 12444600781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10626723396 + 8073921025 = 103086^2 + 89855^2 .

It is a cyclic number.

It is not a de Polignac number, because 18700644421 - 2¹⁵ = 18700611653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18700645421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9350322210 + 9350322211.

It is an arithmetic number, because the mean of its divisors is an integer number (9350322211).

Almost surely, 2^18700644421 is an apocalyptic number.

It is an amenable number.

18700644421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18700644421 is an equidigital number, since it uses as much as digits as its factorization.

18700644421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43008, while the sum is 37.

The spelling of 18700644421 in words is "eighteen billion, seven hundred million, six hundred forty-four thousand, four hundred twenty-one".