21440427 has 16 divisors (see below), whose sum is σ = 29521440. Its totient is φ = 13830912.

The previous prime is 21440411. The next prime is 21440431. The reversal of 21440427 is 72404412.

It is not a de Polignac number, because 21440427 - 2⁴ = 21440411 is a prime.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21440397 and 21440406.

It is not an unprimeable number, because it can be changed into a prime (21440527) 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, 25449 + ... + 26277.

It is an arithmetic number, because the mean of its divisors is an integer number (1845090).

Almost surely, 2^21440427 is an apocalyptic number.

21440427 is a deficient number, since it is larger than the sum of its proper divisors (8081013).

21440427 is a wasteful number, since it uses less digits than its factorization.

21440427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1102.

The product of its (nonzero) digits is 1792, while the sum is 24.

The square root of 21440427 is about 4630.3808698637. The cubic root of 21440427 is about 277.8078265745.

Adding to 21440427 its reverse (72404412), we get a palindrome (93844839).

The spelling of 21440427 in words is "twenty-one million, four hundred forty thousand, four hundred twenty-seven".