21872406 has 16 divisors (see below), whose sum is σ = 44344944. Its totient is φ = 7190784.

The previous prime is 21872399. The next prime is 21872407. The reversal of 21872406 is 60427812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21872407) 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, 24531 + ... + 25406.

It is an arithmetic number, because the mean of its divisors is an integer number (2771559).

Almost surely, 2^21872406 is an apocalyptic number.

21872406 is an abundant number, since it is smaller than the sum of its proper divisors (22472538).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21872406 is a wasteful number, since it uses less digits than its factorization.

21872406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50015.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21872406 is about 4676.7944149813. The cubic root of 21872406 is about 279.6611803058.

The spelling of 21872406 in words is "twenty-one million, eight hundred seventy-two thousand, four hundred six".