21253001 has 32 divisors (see below), whose sum is σ = 28416000. Its totient is φ = 15396480.

The previous prime is 21252997. The next prime is 21253007. The reversal of 21253001 is 10035212.

It is a happy number.

It is not a de Polignac number, because 21253001 - 2² = 21252997 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 (21253007) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106700 + ... + 106898.

It is an arithmetic number, because the mean of its divisors is an integer number (888000).

Almost surely, 2^21253001 is an apocalyptic number.

It is an amenable number.

21253001 is a deficient number, since it is larger than the sum of its proper divisors (7162999).

21253001 is a wasteful number, since it uses less digits than its factorization.

21253001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309.

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

The square root of 21253001 is about 4610.0977213070. The cubic root of 21253001 is about 276.9959510588.

Adding to 21253001 its reverse (10035212), we get a palindrome (31288213).

The spelling of 21253001 in words is "twenty-one million, two hundred fifty-three thousand, one".