21936487 has 2 divisors, whose sum is σ = 21936488. Its totient is φ = 21936486.

The previous prime is 21936463. The next prime is 21936521. The reversal of 21936487 is 78463912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21936487 - 2¹⁵ = 21903719 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21936787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10968243 + 10968244.

It is an arithmetic number, because the mean of its divisors is an integer number (10968244).

Almost surely, 2^21936487 is an apocalyptic number.

21936487 is a deficient number, since it is larger than the sum of its proper divisors (1).

21936487 is an equidigital number, since it uses as much as digits as its factorization.

21936487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 40.

The square root of 21936487 is about 4683.6403576705. The cubic root of 21936487 is about 279.9340278245.

The spelling of 21936487 in words is "twenty-one million, nine hundred thirty-six thousand, four hundred eighty-seven".