21294989 has 2 divisors, whose sum is σ = 21294990. Its totient is φ = 21294988.

The previous prime is 21294937. The next prime is 21295013. The reversal of 21294989 is 98949212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13912900 + 7382089 = 3730^2 + 2717^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21294989 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21294089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10647494 + 10647495.

It is an arithmetic number, because the mean of its divisors is an integer number (10647495).

Almost surely, 2^21294989 is an apocalyptic number.

It is an amenable number.

21294989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21294989 is an equidigital number, since it uses as much as digits as its factorization.

21294989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 44.

The square root of 21294989 is about 4614.6493907988. The cubic root of 21294989 is about 277.1782446121.

The spelling of 21294989 in words is "twenty-one million, two hundred ninety-four thousand, nine hundred eighty-nine".