21505510025 has 48 divisors (see below), whose sum is σ = 28186195968. Its totient is φ = 16244712000.

The previous prime is 21505510001. The next prime is 21505510043. The reversal of 21505510025 is 52001550512.

It is not a de Polignac number, because 21505510025 - 2¹² = 21505505929 is a prime.

It is a super-2 number, since 2×21505510025² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21505509976 and 21505510003.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 26516870 + ... + 26517680.

It is an arithmetic number, because the mean of its divisors is an integer number (587212416).

Almost surely, 2^21505510025 is an apocalyptic number.

21505510025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21505510025 is a deficient number, since it is larger than the sum of its proper divisors (6680685943).

21505510025 is a wasteful number, since it uses less digits than its factorization.

21505510025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1382 (or 1377 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 26.

The spelling of 21505510025 in words is "twenty-one billion, five hundred five million, five hundred ten thousand, twenty-five".