21011625 has 48 divisors (see below), whose sum is σ = 39911040. Its totient is φ = 10605600.

The previous prime is 21011623. The next prime is 21011629. The reversal of 21011625 is 52611012.

It is not a de Polignac number, because 21011625 - 2¹ = 21011623 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21011598 and 21011607.

It is not an unprimeable number, because it can be changed into a prime (21011621) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20884 + ... + 21866.

It is an arithmetic number, because the mean of its divisors is an integer number (831480).

Almost surely, 2^21011625 is an apocalyptic number.

21011625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21011625 is a deficient number, since it is larger than the sum of its proper divisors (18899415).

21011625 is a wasteful number, since it uses less digits than its factorization.

21011625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1023 (or 1010 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21011625 is about 4583.8439109551. The cubic root of 21011625 is about 275.9433169671.

Adding to 21011625 its reverse (52611012), we get a palindrome (73622637).

The spelling of 21011625 in words is "twenty-one million, eleven thousand, six hundred twenty-five".