21727487 has 2 divisors, whose sum is σ = 21727488. Its totient is φ = 21727486.

The previous prime is 21727477. The next prime is 21727493. The reversal of 21727487 is 78472712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21727487 - 2⁸ = 21727231 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21727487.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21727477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863743 + 10863744.

It is an arithmetic number, because the mean of its divisors is an integer number (10863744).

Almost surely, 2^21727487 is an apocalyptic number.

21727487 is a deficient number, since it is larger than the sum of its proper divisors (1).

21727487 is an equidigital number, since it uses as much as digits as its factorization.

21727487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43904, while the sum is 38.

The square root of 21727487 is about 4661.2752546916. The cubic root of 21727487 is about 279.0421650622.

The spelling of 21727487 in words is "twenty-one million, seven hundred twenty-seven thousand, four hundred eighty-seven".