21422081 has 4 divisors (see below), whose sum is σ = 21431472. Its totient is φ = 21412692.

The previous prime is 21422077. The next prime is 21422099. The reversal of 21422081 is 18022412.

It is a happy number.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21422081 - 2² = 21422077 is a prime.

It is a super-2 number, since 2×21422081² = 917811108741122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21422021) 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, 1166 + ... + 6648.

It is an arithmetic number, because the mean of its divisors is an integer number (5357868).

It is a Proth number, since it is equal to 2615 ⋅ 2¹³ + 1 and 2615 < 2¹³.

Almost surely, 2^21422081 is an apocalyptic number.

It is an amenable number.

21422081 is a deficient number, since it is larger than the sum of its proper divisors (9391).

21422081 is an equidigital number, since it uses as much as digits as its factorization.

21422081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9390.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21422081 is about 4628.3993993604. The cubic root of 21422081 is about 277.7285663874.

Adding to 21422081 its reverse (18022412), we get a palindrome (39444493).

The spelling of 21422081 in words is "twenty-one million, four hundred twenty-two thousand, eighty-one".