21081427 has 8 divisors (see below), whose sum is σ = 21748032. Its totient is φ = 20424000.

The previous prime is 21081413. The next prime is 21081433. The reversal of 21081427 is 72418012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21081427 - 2⁷ = 21081299 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21081497) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2527 + ... + 6967.

It is an arithmetic number, because the mean of its divisors is an integer number (2718504).

Almost surely, 2^21081427 is an apocalyptic number.

21081427 is a deficient number, since it is larger than the sum of its proper divisors (666605).

21081427 is a wasteful number, since it uses less digits than its factorization.

21081427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4589.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21081427 is about 4591.4515134105. The cubic root of 21081427 is about 276.2485465004.

Adding to 21081427 its reverse (72418012), we get a palindrome (93499439).

The spelling of 21081427 in words is "twenty-one million, eighty-one thousand, four hundred twenty-seven".