21129587 has 2 divisors, whose sum is σ = 21129588. Its totient is φ = 21129586.

The previous prime is 21129583. The next prime is 21129613. The reversal of 21129587 is 78592112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21129587 - 2² = 21129583 is a prime.

It is not a weakly prime, because it can be changed into another prime (21129583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10564793 + 10564794.

It is an arithmetic number, because the mean of its divisors is an integer number (10564794).

Almost surely, 2^21129587 is an apocalyptic number.

21129587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21129587 is an equidigital number, since it uses as much as digits as its factorization.

21129587 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 35.

The square root of 21129587 is about 4596.6930504440. The cubic root of 21129587 is about 276.4587475121.

The spelling of 21129587 in words is "twenty-one million, one hundred twenty-nine thousand, five hundred eighty-seven".