21247487 has 2 divisors, whose sum is σ = 21247488. Its totient is φ = 21247486.

The previous prime is 21247483. The next prime is 21247519. The reversal of 21247487 is 78474212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21247487 - 2² = 21247483 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21247483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10623743 + 10623744.

It is an arithmetic number, because the mean of its divisors is an integer number (10623744).

Almost surely, 2^21247487 is an apocalyptic number.

21247487 is a deficient number, since it is larger than the sum of its proper divisors (1).

21247487 is an equidigital number, since it uses as much as digits as its factorization.

21247487 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25088, while the sum is 35.

The square root of 21247487 is about 4609.4996474672. The cubic root of 21247487 is about 276.9719938495.

The spelling of 21247487 in words is "twenty-one million, two hundred forty-seven thousand, four hundred eighty-seven".