21051822 has 48 divisors (see below), whose sum is σ = 46884096. Its totient is φ = 6296400.

The previous prime is 21051809. The next prime is 21051839. The reversal of 21051822 is 22815012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 77547 + ... + 77817.

It is an arithmetic number, because the mean of its divisors is an integer number (976752).

Almost surely, 2^21051822 is an apocalyptic number.

21051822 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21051822, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23442048).

21051822 is an abundant number, since it is smaller than the sum of its proper divisors (25832274).

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

21051822 is a wasteful number, since it uses less digits than its factorization.

21051822 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405 (or 394 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21051822 is about 4588.2264547426. The cubic root of 21051822 is about 276.1191724384.

Adding to 21051822 its reverse (22815012), we get a palindrome (43866834).

The spelling of 21051822 in words is "twenty-one million, fifty-one thousand, eight hundred twenty-two".