18501009421 has 2 divisors, whose sum is σ = 18501009422. Its totient is φ = 18501009420.

The previous prime is 18501009409. The next prime is 18501009427. The reversal of 18501009421 is 12490010581.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16290693225 + 2210316196 = 127635^2 + 47014^2 .

It is a cyclic number.

It is not a de Polignac number, because 18501009421 - 2¹¹ = 18501007373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18501009427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9250504710 + 9250504711.

It is an arithmetic number, because the mean of its divisors is an integer number (9250504711).

Almost surely, 2^18501009421 is an apocalyptic number.

It is an amenable number.

18501009421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18501009421 is an equidigital number, since it uses as much as digits as its factorization.

18501009421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2880, while the sum is 31.

The spelling of 18501009421 in words is "eighteen billion, five hundred one million, nine thousand, four hundred twenty-one".