21818797 has 32 divisors (see below), whose sum is σ = 29804544. Its totient is φ = 15422400.

The previous prime is 21818779. The next prime is 21818801. The reversal of 21818797 is 79781812.

It is a happy number.

It is not a de Polignac number, because 21818797 - 2¹¹ = 21816749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21818747) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 70918 + ... + 71224.

It is an arithmetic number, because the mean of its divisors is an integer number (931392).

Almost surely, 2^21818797 is an apocalyptic number.

It is an amenable number.

21818797 is a deficient number, since it is larger than the sum of its proper divisors (7985747).

21818797 is a wasteful number, since it uses less digits than its factorization.

21818797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409.

The product of its digits is 56448, while the sum is 43.

The square root of 21818797 is about 4671.0595157844. The cubic root of 21818797 is about 279.4325113364.

It can be divided in two parts, 21 and 818797, that added together give a palindrome (818818).

The spelling of 21818797 in words is "twenty-one million, eight hundred eighteen thousand, seven hundred ninety-seven".