21499481 has 2 divisors, whose sum is σ = 21499482. Its totient is φ = 21499480.

The previous prime is 21499477. The next prime is 21499483. The reversal of 21499481 is 18499412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11833600 + 9665881 = 3440^2 + 3109^2 .

It is a cyclic number.

It is not a de Polignac number, because 21499481 - 2² = 21499477 is a prime.

It is a super-2 number, since 2×21499481² = 924455366538722, which contains 22 as substring.

Together with 21499483, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21499483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10749740 + 10749741.

It is an arithmetic number, because the mean of its divisors is an integer number (10749741).

Almost surely, 2^21499481 is an apocalyptic number.

It is an amenable number.

21499481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21499481 is an equidigital number, since it uses as much as digits as its factorization.

21499481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20736, while the sum is 38.

The square root of 21499481 is about 4636.7532822008. The cubic root of 21499481 is about 278.0626508557.

The spelling of 21499481 in words is "twenty-one million, four hundred ninety-nine thousand, four hundred eighty-one".