21017406 has 32 divisors (see below), whose sum is σ = 45718560. Its totient is φ = 6414336.

The previous prime is 21017371. The next prime is 21017407. The reversal of 21017406 is 60471012.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21017407) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 990 + ... + 6558.

It is an arithmetic number, because the mean of its divisors is an integer number (1428705).

Almost surely, 2^21017406 is an apocalyptic number.

21017406 is an abundant number, since it is smaller than the sum of its proper divisors (24701154).

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

21017406 is a wasteful number, since it uses less digits than its factorization.

21017406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5628.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21017406 is about 4584.4744518865. The cubic root of 21017406 is about 275.9686217216.

Adding to 21017406 its reverse (60471012), we get a palindrome (81488418).

The spelling of 21017406 in words is "twenty-one million, seventeen thousand, four hundred six".