21050406 has 24 divisors (see below), whose sum is σ = 49118160. Its totient is φ = 6476976.

The previous prime is 21050401. The next prime is 21050413. The reversal of 21050406 is 60405012.

It is a happy number.

21050406 is a `hidden beast` number, since 210 + 50 + 406 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44746 + ... + 45213.

It is an arithmetic number, because the mean of its divisors is an integer number (2046590).

Almost surely, 2^21050406 is an apocalyptic number.

21050406 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21050406 is an abundant number, since it is smaller than the sum of its proper divisors (28067754).

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

21050406 is a wasteful number, since it uses less digits than its factorization.

21050406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89980 (or 89977 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21050406 is about 4588.0721441582. The cubic root of 21050406 is about 276.1129814696.

Adding to 21050406 its reverse (60405012), we get a palindrome (81455418).

The spelling of 21050406 in words is "twenty-one million, fifty thousand, four hundred six".