21125427 has 16 divisors (see below), whose sum is σ = 29821440. Its totient is φ = 13279392.

The previous prime is 21125393. The next prime is 21125443. The reversal of 21125427 is 72452112.

It is not a de Polignac number, because 21125427 - 2²³ = 12736819 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21125397 and 21125406.

It is not an unprimeable number, because it can be changed into a prime (21125227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 918 + ... + 6564.

It is an arithmetic number, because the mean of its divisors is an integer number (1863840).

Almost surely, 2^21125427 is an apocalyptic number.

21125427 is a deficient number, since it is larger than the sum of its proper divisors (8696013).

21125427 is a wasteful number, since it uses less digits than its factorization.

21125427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5722.

The product of its digits is 1120, while the sum is 24.

The square root of 21125427 is about 4596.2405289541. The cubic root of 21125427 is about 276.4406032251.

Adding to 21125427 its reverse (72452112), we get a palindrome (93577539).

The spelling of 21125427 in words is "twenty-one million, one hundred twenty-five thousand, four hundred twenty-seven".