21427769 has 16 divisors (see below), whose sum is σ = 24981696. Its totient is φ = 18314560.

The previous prime is 21427751. The next prime is 21427771. The reversal of 21427769 is 96772412.

It is not a de Polignac number, because 21427769 - 2¹² = 21423673 is a prime.

It is a super-2 number, since 2×21427769² = 918298568634722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427709) 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, 22154 + ... + 23100.

It is an arithmetic number, because the mean of its divisors is an integer number (1561356).

Almost surely, 2^21427769 is an apocalyptic number.

It is an amenable number.

21427769 is a deficient number, since it is larger than the sum of its proper divisors (3553927).

21427769 is an equidigital number, since it uses as much as digits as its factorization.

21427769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 997 (or 975 counting only the distinct ones).

The product of its digits is 42336, while the sum is 38.

The square root of 21427769 is about 4629.0138258597. The cubic root of 21427769 is about 277.7531450809.

The spelling of 21427769 in words is "twenty-one million, four hundred twenty-seven thousand, seven hundred sixty-nine".