21010625 has 10 divisors (see below), whose sum is σ = 26255658. Its totient is φ = 16808000.

The previous prime is 21010609. The next prime is 21010663. The reversal of 21010625 is 52601012.

It can be written as a sum of positive squares in 5 ways, for example, as 12623809 + 8386816 = 3553^2 + 2896^2 .

It is not a de Polignac number, because 21010625 - 2⁴ = 21010609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 16184 + ... + 17433.

Almost surely, 2^21010625 is an apocalyptic number.

21010625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21010625 is a deficient number, since it is larger than the sum of its proper divisors (5245033).

21010625 is an frugal number, since it uses more digits than its factorization.

21010625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33637 (or 33622 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21010625 is about 4583.7348308994. The cubic root of 21010625 is about 275.9389392683.

Adding to 21010625 its reverse (52601012), we get a palindrome (73611637).

The spelling of 21010625 in words is "twenty-one million, ten thousand, six hundred twenty-five".