21564370 has 8 divisors (see below), whose sum is σ = 38815884. Its totient is φ = 8625744.

The previous prime is 21564353. The next prime is 21564379. The reversal of 21564370 is 7346512.

It can be written as a sum of positive squares in 2 ways, for example, as 21242881 + 321489 = 4609^2 + 567^2 .

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 (21564379) 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 3 ways as a sum of consecutive naturals, for example, 1078209 + ... + 1078228.

Almost surely, 2^21564370 is an apocalyptic number.

21564370 is a deficient number, since it is larger than the sum of its proper divisors (17251514).

21564370 is a wasteful number, since it uses less digits than its factorization.

21564370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2156444.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21564370 is about 4643.7452557176. The cubic root of 21564370 is about 278.3421162881.

The spelling of 21564370 in words is "twenty-one million, five hundred sixty-four thousand, three hundred seventy".