21283987 has 2 divisors, whose sum is σ = 21283988. Its totient is φ = 21283986.

The previous prime is 21283979. The next prime is 21284041. The reversal of 21283987 is 78938212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21283987 - 2³ = 21283979 is a prime.

It is not a weakly prime, because it can be changed into another prime (21283967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10641993 + 10641994.

It is an arithmetic number, because the mean of its divisors is an integer number (10641994).

Almost surely, 2^21283987 is an apocalyptic number.

21283987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21283987 is an equidigital number, since it uses as much as digits as its factorization.

21283987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 40.

The square root of 21283987 is about 4613.4571635597. The cubic root of 21283987 is about 277.1305019190.

The spelling of 21283987 in words is "twenty-one million, two hundred eighty-three thousand, nine hundred eighty-seven".