21270751 has 2 divisors, whose sum is σ = 21270752. Its totient is φ = 21270750.

The previous prime is 21270719. The next prime is 21270763. The reversal of 21270751 is 15707212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21270751 - 2⁵ = 21270719 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21270551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10635375 + 10635376.

It is an arithmetic number, because the mean of its divisors is an integer number (10635376).

Almost surely, 2^21270751 is an apocalyptic number.

21270751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21270751 is an equidigital number, since it uses as much as digits as its factorization.

21270751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21270751 is about 4612.0224414025. The cubic root of 21270751 is about 277.0730430736.

Adding to 21270751 its reverse (15707212), we get a palindrome (36977963).

The spelling of 21270751 in words is "twenty-one million, two hundred seventy thousand, seven hundred fifty-one".