21380473 has 2 divisors, whose sum is σ = 21380474. Its totient is φ = 21380472.

The previous prime is 21380467. The next prime is 21380519. The reversal of 21380473 is 37408312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20820969 + 559504 = 4563^2 + 748^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21380473 is a prime.

It is a plaindrome in base 13.

It is not a weakly prime, because it can be changed into another prime (21380423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10690236 + 10690237.

It is an arithmetic number, because the mean of its divisors is an integer number (10690237).

Almost surely, 2^21380473 is an apocalyptic number.

It is an amenable number.

21380473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21380473 is an equidigital number, since it uses as much as digits as its factorization.

21380473 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21380473 is about 4623.9023562355. The cubic root of 21380473 is about 277.5486395816.

Adding to 21380473 its reverse (37408312), we get a palindrome (58788785).

The spelling of 21380473 in words is "twenty-one million, three hundred eighty thousand, four hundred seventy-three".