21456406 has 4 divisors (see below), whose sum is σ = 32184612. Its totient is φ = 10728202.

The previous prime is 21456403. The next prime is 21456419. The reversal of 21456406 is 60465412.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5364100 + ... + 5364103.

It is an arithmetic number, because the mean of its divisors is an integer number (8046153).

Almost surely, 2^21456406 is an apocalyptic number.

21456406 is a deficient number, since it is larger than the sum of its proper divisors (10728206).

21456406 is a wasteful number, since it uses less digits than its factorization.

21456406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10728205.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 21456406 is about 4632.1060005142. The cubic root of 21456406 is about 277.8768237846.

The spelling of 21456406 in words is "twenty-one million, four hundred fifty-six thousand, four hundred six".