21425547 has 16 divisors (see below), whose sum is σ = 33562368. Its totient is φ = 11986080.

The previous prime is 21425539. The next prime is 21425549. The reversal of 21425547 is 74552412.

It is not a de Polignac number, because 21425547 - 2³ = 21425539 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21425549) 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, 24543 + ... + 25400.

It is an arithmetic number, because the mean of its divisors is an integer number (2097648).

Almost surely, 2^21425547 is an apocalyptic number.

21425547 is a deficient number, since it is larger than the sum of its proper divisors (12136821).

21425547 is a wasteful number, since it uses less digits than its factorization.

21425547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49970.

The product of its digits is 11200, while the sum is 30.

The square root of 21425547 is about 4628.7738117130. The cubic root of 21425547 is about 277.7435440063.

Adding to 21425547 its reverse (74552412), we get a palindrome (95977959).

The spelling of 21425547 in words is "twenty-one million, four hundred twenty-five thousand, five hundred forty-seven".