21031025 has 6 divisors (see below), whose sum is σ = 26078502. Its totient is φ = 16824800.

The previous prime is 21031019. The next prime is 21031027. The reversal of 21031025 is 52013012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 4376464 + 16654561 = 2092^2 + 4081^2 .

It is not a de Polignac number, because 21031025 - 2⁴ = 21031009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21031027) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 420596 + ... + 420645.

It is an arithmetic number, because the mean of its divisors is an integer number (4346417).

Almost surely, 2^21031025 is an apocalyptic number.

21031025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21031025 is a deficient number, since it is larger than the sum of its proper divisors (5047477).

21031025 is an equidigital number, since it uses as much as digits as its factorization.

21031025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 841251 (or 841246 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21031025 is about 4585.9595506284. The cubic root of 21031025 is about 276.0282168519.

Adding to 21031025 its reverse (52013012), we get a palindrome (73044037).

The spelling of 21031025 in words is "twenty-one million, thirty-one thousand, twenty-five".