20625021 has 24 divisors (see below), whose sum is σ = 30843384. Its totient is φ = 13271040.

The previous prime is 20625019. The next prime is 20625023. The reversal of 20625021 is 12052602.

20625021 is a `hidden beast` number, since 20 + 625 + 0 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (20625019) and next prime (20625023).

It can be written as a sum of positive squares in 4 ways, for example, as 16088121 + 4536900 = 4011^2 + 2130^2 .

It is not a de Polignac number, because 20625021 - 2¹ = 20625019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20624985 and 20625003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20625023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 80125 + ... + 80381.

It is an arithmetic number, because the mean of its divisors is an integer number (1285141).

Almost surely, 2^20625021 is an apocalyptic number.

It is an amenable number.

20625021 is a deficient number, since it is larger than the sum of its proper divisors (10218363).

20625021 is a wasteful number, since it uses less digits than its factorization.

20625021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541 (or 538 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 20625021 is about 4541.4778431696. The cubic root of 20625021 is about 274.2404206971.

Adding to 20625021 its reverse (12052602), we get a palindrome (32677623).

The spelling of 20625021 in words is "twenty million, six hundred twenty-five thousand, twenty-one".