21651427 has 4 divisors (see below), whose sum is σ = 24744496. Its totient is φ = 18558360.

The previous prime is 21651419. The next prime is 21651439. The reversal of 21651427 is 72415612.

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 21651427 - 2³ = 21651419 is a prime.

It is a super-2 number, since 2×21651427² = 937568582272658, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21651395 and 21651404.

It is not an unprimeable number, because it can be changed into a prime (21652427) 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, 1546524 + ... + 1546537.

It is an arithmetic number, because the mean of its divisors is an integer number (6186124).

Almost surely, 2^21651427 is an apocalyptic number.

21651427 is a deficient number, since it is larger than the sum of its proper divisors (3093069).

21651427 is an equidigital number, since it uses as much as digits as its factorization.

21651427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3093068.

The product of its digits is 3360, while the sum is 28.

The square root of 21651427 is about 4653.1093905044. The cubic root of 21651427 is about 278.7161761261.

The spelling of 21651427 in words is "twenty-one million, six hundred fifty-one thousand, four hundred twenty-seven".