21251361 has 8 divisors (see below), whose sum is σ = 28374304. Its totient is φ = 14148000.

The previous prime is 21251353. The next prime is 21251381. The reversal of 21251361 is 16315212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21251361 - 2³ = 21251353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21251311) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2140 + ... + 6861.

It is an arithmetic number, because the mean of its divisors is an integer number (3546788).

Almost surely, 2^21251361 is an apocalyptic number.

It is an amenable number.

21251361 is a deficient number, since it is larger than the sum of its proper divisors (7122943).

21251361 is an equidigital number, since it uses as much as digits as its factorization.

21251361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9791.

The product of its digits is 360, while the sum is 21.

The square root of 21251361 is about 4609.9198474594. The cubic root of 21251361 is about 276.9888260251.

Adding to 21251361 its reverse (16315212), we get a palindrome (37566573).

It can be divided in two parts, 21251 and 361, that added together give a palindrome (21612).

The spelling of 21251361 in words is "twenty-one million, two hundred fifty-one thousand, three hundred sixty-one".