21870866 has 8 divisors (see below), whose sum is σ = 32887740. Its totient is φ = 10908288.

The previous prime is 21870859. The next prime is 21870869. The reversal of 21870866 is 66807812.

It can be written as a sum of positive squares in 2 ways, for example, as 19545241 + 2325625 = 4421^2 + 1525^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21870869) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12551 + ... + 14186.

Almost surely, 2^21870866 is an apocalyptic number.

21870866 is a deficient number, since it is larger than the sum of its proper divisors (11016874).

21870866 is a wasteful number, since it uses less digits than its factorization.

21870866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27148.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 21870866 is about 4676.6297693959. The cubic root of 21870866 is about 279.6546166577.

The spelling of 21870866 in words is "twenty-one million, eight hundred seventy thousand, eight hundred sixty-six".