21145425 has 24 divisors (see below), whose sum is σ = 39955776. Its totient is φ = 9666240.

The previous prime is 21145417. The next prime is 21145427. The reversal of 21145425 is 52454112.

It is not a de Polignac number, because 21145425 - 2³ = 21145417 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21145395 and 21145404.

It is not an unprimeable number, because it can be changed into a prime (21145427) 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 23 ways as a sum of consecutive naturals, for example, 19614 + ... + 20663.

It is an arithmetic number, because the mean of its divisors is an integer number (1664824).

Almost surely, 2^21145425 is an apocalyptic number.

21145425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21145425 is a deficient number, since it is larger than the sum of its proper divisors (18810351).

21145425 is a wasteful number, since it uses less digits than its factorization.

21145425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40297 (or 40292 counting only the distinct ones).

The product of its digits is 1600, while the sum is 24.

The square root of 21145425 is about 4598.4154879697. The cubic root of 21145425 is about 276.5278048659.

Adding to 21145425 its reverse (52454112), we get a palindrome (73599537).

The spelling of 21145425 in words is "twenty-one million, one hundred forty-five thousand, four hundred twenty-five".