21451489 has 2 divisors, whose sum is σ = 21451490. Its totient is φ = 21451488.

The previous prime is 21451483. The next prime is 21451499. The reversal of 21451489 is 98415412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17707264 + 3744225 = 4208^2 + 1935^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21451489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21451483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725744 + 10725745.

It is an arithmetic number, because the mean of its divisors is an integer number (10725745).

Almost surely, 2^21451489 is an apocalyptic number.

It is an amenable number.

21451489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21451489 is an equidigital number, since it uses as much as digits as its factorization.

21451489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 34.

The square root of 21451489 is about 4631.5752180009. The cubic root of 21451489 is about 277.8555958628.

The spelling of 21451489 in words is "twenty-one million, four hundred fifty-one thousand, four hundred eighty-nine".