21478189 has 4 divisors (see below), whose sum is σ = 22608640. Its totient is φ = 20347740.

The previous prime is 21478187. The next prime is 21478207. The reversal of 21478189 is 98187412.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21478189 - 2¹ = 21478187 is a prime.

It is a super-2 number, since 2×21478189² = 922625205439442, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478187) 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, 565197 + ... + 565234.

It is an arithmetic number, because the mean of its divisors is an integer number (5652160).

Almost surely, 2^21478189 is an apocalyptic number.

It is an amenable number.

21478189 is a deficient number, since it is larger than the sum of its proper divisors (1130451).

21478189 is a wasteful number, since it uses less digits than its factorization.

21478189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1130450.

The product of its digits is 32256, while the sum is 40.

The square root of 21478189 is about 4634.4567103383. The cubic root of 21478189 is about 277.9708274686.

The spelling of 21478189 in words is "twenty-one million, four hundred seventy-eight thousand, one hundred eighty-nine".