21224878 has 8 divisors (see below), whose sum is σ = 31884840. Its totient is φ = 10596600.

The previous prime is 21224867. The next prime is 21224893. The reversal of 21224878 is 87842212.

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

It is a super-2 number, since 2×21224878² = 900990892229768, which contains 22 as substring.

It is a congruent number.

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, 6168 + ... + 8971.

It is an arithmetic number, because the mean of its divisors is an integer number (3985605).

Almost surely, 2^21224878 is an apocalyptic number.

21224878 is a deficient number, since it is larger than the sum of its proper divisors (10659962).

21224878 is a wasteful number, since it uses less digits than its factorization.

21224878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15842.

The product of its digits is 14336, while the sum is 34.

The square root of 21224878 is about 4607.0465593480. The cubic root of 21224878 is about 276.8737189769.

The spelling of 21224878 in words is "twenty-one million, two hundred twenty-four thousand, eight hundred seventy-eight".