21421273 has 2 divisors, whose sum is σ = 21421274. Its totient is φ = 21421272.

The previous prime is 21421259. The next prime is 21421319. The reversal of 21421273 is 37212412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20720704 + 700569 = 4552^2 + 837^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421273 - 2⁹ = 21420761 is a prime.

It is not a weakly prime, because it can be changed into another prime (21421243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710636 + 10710637.

It is an arithmetic number, because the mean of its divisors is an integer number (10710637).

Almost surely, 2^21421273 is an apocalyptic number.

It is an amenable number.

21421273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421273 is an equidigital number, since it uses as much as digits as its factorization.

21421273 is an evil number, because the sum of its binary digits is even.

The product of its digits is 672, while the sum is 22.

The square root of 21421273 is about 4628.3121113425. The cubic root of 21421273 is about 277.7250745463.

Adding to 21421273 its reverse (37212412), we get a palindrome (58633685).

The spelling of 21421273 in words is "twenty-one million, four hundred twenty-one thousand, two hundred seventy-three".