21874945 has 8 divisors (see below), whose sum is σ = 26289000. Its totient is φ = 17473920.

The previous prime is 21874943. The next prime is 21874991. The reversal of 21874945 is 54947812.

It can be written as a sum of positive squares in 4 ways, for example, as 2900209 + 18974736 = 1703^2 + 4356^2 .

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

It is not a de Polignac number, because 21874945 - 2¹ = 21874943 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21874898 and 21874907.

It is not an unprimeable number, because it can be changed into a prime (21874943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 931 + ... + 6679.

It is an arithmetic number, because the mean of its divisors is an integer number (3286125).

Almost surely, 2^21874945 is an apocalyptic number.

It is an amenable number.

21874945 is a deficient number, since it is larger than the sum of its proper divisors (4414055).

21874945 is an equidigital number, since it uses as much as digits as its factorization.

21874945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6515.

The product of its digits is 80640, while the sum is 40.

The square root of 21874945 is about 4677.0658537164. The cubic root of 21874945 is about 279.6720011282.

The spelling of 21874945 in words is "twenty-one million, eight hundred seventy-four thousand, nine hundred forty-five".