21478891025 has 12 divisors (see below), whose sum is σ = 26640397212. Its totient is φ = 17178872640.

The previous prime is 21478891003. The next prime is 21478891037. The reversal of 21478891025 is 52019887412.

It can be written as a sum of positive squares in 6 ways, for example, as 68178049 + 21410712976 = 8257^2 + 146324^2 .

It is not a de Polignac number, because 21478891025 - 2¹⁰ = 21478890001 is a prime.

It is a super-2 number, since 2×21478891025² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (47) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

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, 614 + ... + 207263.

It is an arithmetic number, because the mean of its divisors is an integer number (2220033101).

Almost surely, 2^21478891025 is an apocalyptic number.

21478891025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21478891025 is a deficient number, since it is larger than the sum of its proper divisors (5161506187).

21478891025 is a wasteful number, since it uses less digits than its factorization.

21478891025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212020 (or 212015 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 47.

The spelling of 21478891025 in words is "twenty-one billion, four hundred seventy-eight million, eight hundred ninety-one thousand, twenty-five".