21878330 has 8 divisors (see below), whose sum is σ = 39381012. Its totient is φ = 8751328.

The previous prime is 21878327. The next prime is 21878341. The reversal of 21878330 is 3387812.

It can be written as a sum of positive squares in 2 ways, for example, as 21335161 + 543169 = 4619^2 + 737^2 .

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

It is a super-2 number, since 2×21878330² = 957322647177800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093907 + ... + 1093926.

Almost surely, 2^21878330 is an apocalyptic number.

21878330 is a deficient number, since it is larger than the sum of its proper divisors (17502682).

21878330 is a wasteful number, since it uses less digits than its factorization.

21878330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187840.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 21878330 is about 4677.4277118946. The cubic root of 21878330 is about 279.6864261686.

The spelling of 21878330 in words is "twenty-one million, eight hundred seventy-eight thousand, three hundred thirty".