21456481 has 2 divisors, whose sum is σ = 21456482. Its totient is φ = 21456480.

The previous prime is 21456469. The next prime is 21456503. The reversal of 21456481 is 18465412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13075456 + 8381025 = 3616^2 + 2895^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21456481 is a prime.

It is a super-2 number, since 2×21456481² = 920761153806722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21456181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728240 + 10728241.

It is an arithmetic number, because the mean of its divisors is an integer number (10728241).

Almost surely, 2^21456481 is an apocalyptic number.

It is an amenable number.

21456481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21456481 is an equidigital number, since it uses as much as digits as its factorization.

21456481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 31.

The square root of 21456481 is about 4632.1140961768. The cubic root of 21456481 is about 277.8771475533.

The spelling of 21456481 in words is "twenty-one million, four hundred fifty-six thousand, four hundred eighty-one".