21503316425 has 12 divisors (see below), whose sum is σ = 26731288716. Its totient is φ = 17159313600.

The previous prime is 21503316413. The next prime is 21503316431. The reversal of 21503316425 is 52461330512.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3627893824 + 17875422601 = 60232^2 + 133699^2 .

It is not a de Polignac number, because 21503316425 - 2¹⁰ = 21503315401 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21503316391 and 21503316400.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1073366 + ... + 1093215.

It is an arithmetic number, because the mean of its divisors is an integer number (2227607393).

Almost surely, 2^21503316425 is an apocalyptic number.

21503316425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21503316425 is a deficient number, since it is larger than the sum of its proper divisors (5227972291).

21503316425 is a wasteful number, since it uses less digits than its factorization.

21503316425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2166988 (or 2166983 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 32.

Adding to 21503316425 its reverse (52461330512), we get a palindrome (73964646937).

The spelling of 21503316425 in words is "twenty-one billion, five hundred three million, three hundred sixteen thousand, four hundred twenty-five".