21864278 has 16 divisors (see below), whose sum is σ = 35074944. Its totient is φ = 10185600.

The previous prime is 21864263. The next prime is 21864281. The reversal of 21864278 is 87246812.

It is a super-2 number, since 2×21864278² = 956093304922568, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 251 + ... + 6617.

It is an arithmetic number, because the mean of its divisors is an integer number (2192184).

Almost surely, 2^21864278 is an apocalyptic number.

21864278 is a deficient number, since it is larger than the sum of its proper divisors (13210666).

21864278 is a wasteful number, since it uses less digits than its factorization.

21864278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6487.

The product of its digits is 43008, while the sum is 38.

The square root of 21864278 is about 4675.9253629629. The cubic root of 21864278 is about 279.6265344039.

The spelling of 21864278 in words is "twenty-one million, eight hundred sixty-four thousand, two hundred seventy-eight".