21427811 has 4 divisors (see below), whose sum is σ = 21635952. Its totient is φ = 21219672.

The previous prime is 21427807. The next prime is 21427829. The reversal of 21427811 is 11872412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21427811 - 2² = 21427807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427841) 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, 103916 + ... + 104121.

It is an arithmetic number, because the mean of its divisors is an integer number (5408988).

Almost surely, 2^21427811 is an apocalyptic number.

21427811 is a deficient number, since it is larger than the sum of its proper divisors (208141).

21427811 is a wasteful number, since it uses less digits than its factorization.

21427811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208140.

The product of its digits is 896, while the sum is 26.

The square root of 21427811 is about 4629.0183624609. The cubic root of 21427811 is about 277.7533265529.

The spelling of 21427811 in words is "twenty-one million, four hundred twenty-seven thousand, eight hundred eleven".