21427730 has 8 divisors (see below), whose sum is σ = 38569932. Its totient is φ = 8571088.

The previous prime is 21427711. The next prime is 21427751. The reversal of 21427730 is 3772412.

It can be written as a sum of positive squares in 2 ways, for example, as 19882681 + 1545049 = 4459^2 + 1243^2 .

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

It is a super-2 number, since 2×21427730² = 918295225905800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21427730.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1071377 + ... + 1071396.

Almost surely, 2^21427730 is an apocalyptic number.

21427730 is a deficient number, since it is larger than the sum of its proper divisors (17142202).

21427730 is a wasteful number, since it uses less digits than its factorization.

21427730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2142780.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 21427730 is about 4629.0096132974. The cubic root of 21427730 is about 277.7529765709.

The spelling of 21427730 in words is "twenty-one million, four hundred twenty-seven thousand, seven hundred thirty".