21270351 has 4 divisors (see below), whose sum is σ = 28360472. Its totient is φ = 14180232.

The previous prime is 21270323. The next prime is 21270373. The reversal of 21270351 is 15307212.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21270351 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21270551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3545056 + ... + 3545061.

It is an arithmetic number, because the mean of its divisors is an integer number (7090118).

Almost surely, 2^21270351 is an apocalyptic number.

21270351 is a deficient number, since it is larger than the sum of its proper divisors (7090121).

21270351 is an equidigital number, since it uses as much as digits as its factorization.

21270351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7090120.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21270351 is about 4611.9790762752. The cubic root of 21270351 is about 277.0713062612.

Adding to 21270351 its reverse (15307212), we get a palindrome (36577563).

The spelling of 21270351 in words is "twenty-one million, two hundred seventy thousand, three hundred fifty-one".