21522401 has 4 divisors (see below), whose sum is σ = 22216704. Its totient is φ = 20828100.

The previous prime is 21522373. The next prime is 21522427. The reversal of 21522401 is 10422512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21522401 - 2⁶ = 21522337 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 21522401.

It is not an unprimeable number, because it can be changed into a prime (21522461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 347105 + ... + 347166.

It is an arithmetic number, because the mean of its divisors is an integer number (5554176).

Almost surely, 2^21522401 is an apocalyptic number.

It is an amenable number.

21522401 is a deficient number, since it is larger than the sum of its proper divisors (694303).

21522401 is an equidigital number, since it uses as much as digits as its factorization.

21522401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694302.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21522401 is about 4639.2241808302. The cubic root of 21522401 is about 278.1614273880.

Adding to 21522401 its reverse (10422512), we get a palindrome (31944913).

The spelling of 21522401 in words is "twenty-one million, five hundred twenty-two thousand, four hundred one".