21384787 has 2 divisors, whose sum is σ = 21384788. Its totient is φ = 21384786.

The previous prime is 21384773. The next prime is 21384791. The reversal of 21384787 is 78748312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21384787 is a prime.

It is not a weakly prime, because it can be changed into another prime (21384767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10692393 + 10692394.

It is an arithmetic number, because the mean of its divisors is an integer number (10692394).

Almost surely, 2^21384787 is an apocalyptic number.

21384787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21384787 is an equidigital number, since it uses as much as digits as its factorization.

21384787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 40.

The square root of 21384787 is about 4624.3688217961. The cubic root of 21384787 is about 277.5673055907.

The spelling of 21384787 in words is "twenty-one million, three hundred eighty-four thousand, seven hundred eighty-seven".