21042005025 has 24 divisors (see below), whose sum is σ = 34917856384. Its totient is φ = 11180980800.

The previous prime is 21042005021. The next prime is 21042005123. The reversal of 21042005025 is 52050024012.

It is a happy number.

It is not a de Polignac number, because 21042005025 - 2² = 21042005021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21042004992 and 21042005010.

It is not an unprimeable number, because it can be changed into a prime (21042005021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 497314 + ... + 537963.

Almost surely, 2^21042005025 is an apocalyptic number.

21042005025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21042005025 is a deficient number, since it is larger than the sum of its proper divisors (13875851359).

21042005025 is a wasteful number, since it uses less digits than its factorization.

21042005025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1035561 (or 1035556 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

Adding to 21042005025 its reverse (52050024012), we get a palindrome (73092029037).

The spelling of 21042005025 in words is "twenty-one billion, forty-two million, five thousand, twenty-five".