21247863 has 24 divisors (see below), whose sum is σ = 35065728. Its totient is φ = 11205792.

The previous prime is 21247861. The next prime is 21247867. The reversal of 21247863 is 36874212.

It is not a de Polignac number, because 21247863 - 2¹ = 21247861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 556 + ... + 6542.

It is an arithmetic number, because the mean of its divisors is an integer number (1461072).

Almost surely, 2^21247863 is an apocalyptic number.

21247863 is a deficient number, since it is larger than the sum of its proper divisors (13817865).

21247863 is a wasteful number, since it uses less digits than its factorization.

21247863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6023 (or 6010 counting only the distinct ones).

The product of its digits is 16128, while the sum is 33.

The square root of 21247863 is about 4609.5404326245. The cubic root of 21247863 is about 276.9736276247.

The spelling of 21247863 in words is "twenty-one million, two hundred forty-seven thousand, eight hundred sixty-three".