21240430987 has 2 divisors, whose sum is σ = 21240430988. Its totient is φ = 21240430986.

The previous prime is 21240430979. The next prime is 21240431039. The reversal of 21240430987 is 78903404212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21240430987 - 2³ = 21240430979 is a prime.

It is not a weakly prime, because it can be changed into another prime (21240430957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620215493 + 10620215494.

It is an arithmetic number, because the mean of its divisors is an integer number (10620215494).

Almost surely, 2^21240430987 is an apocalyptic number.

21240430987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240430987 is an equidigital number, since it uses as much as digits as its factorization.

21240430987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96768, while the sum is 40.

The spelling of 21240430987 in words is "twenty-one billion, two hundred forty million, four hundred thirty thousand, nine hundred eighty-seven".