21263816 has 32 divisors (see below), whose sum is σ = 45722880. Its totient is φ = 9081600.

The previous prime is 21263797. The next prime is 21263819. The reversal of 21263816 is 61836212.

It is not an unprimeable number, because it can be changed into a prime (21263819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23696 + ... + 24576.

It is an arithmetic number, because the mean of its divisors is an integer number (1428840).

Almost surely, 2^21263816 is an apocalyptic number.

It is an amenable number.

21263816 is an abundant number, since it is smaller than the sum of its proper divisors (24459064).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21263816 is a wasteful number, since it uses less digits than its factorization.

21263816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325 (or 1321 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 21263816 is about 4611.2705407512. The cubic root of 21263816 is about 277.0429280044.

The spelling of 21263816 in words is "twenty-one million, two hundred sixty-three thousand, eight hundred sixteen".