21803397 has 32 divisors (see below), whose sum is σ = 37238784. Its totient is φ = 11016000.

The previous prime is 21803387. The next prime is 21803407. The reversal of 21803397 is 79330812.

It is an interprime number because it is at equal distance from previous prime (21803387) and next prime (21803407).

It is not a de Polignac number, because 21803397 - 2⁸ = 21803141 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21803377) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7272 + ... + 9822.

It is an arithmetic number, because the mean of its divisors is an integer number (1163712).

Almost surely, 2^21803397 is an apocalyptic number.

It is an amenable number.

21803397 is a deficient number, since it is larger than the sum of its proper divisors (15435387).

21803397 is a wasteful number, since it uses less digits than its factorization.

21803397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2609.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 21803397 is about 4669.4107765327. The cubic root of 21803397 is about 279.3667534564.

It can be divided in two parts, 218033 and 97, that added together give a triangular number (218130 = T₆₆₀).

The spelling of 21803397 in words is "twenty-one million, eight hundred three thousand, three hundred ninety-seven".