21812783 has 2 divisors, whose sum is σ = 21812784. Its totient is φ = 21812782.

The previous prime is 21812759. The next prime is 21812789. The reversal of 21812783 is 38721812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21812783 - 2¹² = 21808687 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 (21812789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906391 + 10906392.

It is an arithmetic number, because the mean of its divisors is an integer number (10906392).

Almost surely, 2^21812783 is an apocalyptic number.

21812783 is a deficient number, since it is larger than the sum of its proper divisors (1).

21812783 is an equidigital number, since it uses as much as digits as its factorization.

21812783 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5376, while the sum is 32.

The square root of 21812783 is about 4670.4157202545. The cubic root of 21812783 is about 279.4068352867.

The spelling of 21812783 in words is "twenty-one million, eight hundred twelve thousand, seven hundred eighty-three".