21016406 has 4 divisors (see below), whose sum is σ = 31524612. Its totient is φ = 10508202.

The previous prime is 21016397. The next prime is 21016409. The reversal of 21016406 is 60461012.

It is a happy number.

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 (21016409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5254100 + ... + 5254103.

It is an arithmetic number, because the mean of its divisors is an integer number (7881153).

Almost surely, 2^21016406 is an apocalyptic number.

21016406 is a deficient number, since it is larger than the sum of its proper divisors (10508206).

21016406 is a wasteful number, since it uses less digits than its factorization.

21016406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10508205.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21016406 is about 4584.3653868338. The cubic root of 21016406 is about 275.9642448256.

Adding to 21016406 its reverse (60461012), we get a palindrome (81477418).

The spelling of 21016406 in words is "twenty-one million, sixteen thousand, four hundred six".