21802291 has 8 divisors (see below), whose sum is σ = 26228480. Its totient is φ = 17704008.

The previous prime is 21802273. The next prime is 21802337. The reversal of 21802291 is 19220812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21802291 - 2⁵ = 21802259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21802271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81831 + ... + 82096.

It is an arithmetic number, because the mean of its divisors is an integer number (3278560).

Almost surely, 2^21802291 is an apocalyptic number.

21802291 is a deficient number, since it is larger than the sum of its proper divisors (4426189).

21802291 is a wasteful number, since it uses less digits than its factorization.

21802291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163953.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21802291 is about 4669.2923446707. The cubic root of 21802291 is about 279.3620296534.

It can be divided in two parts, 2180 and 2291, that multiplied together give a triangular number (4994380 = T₃₁₆₀).

The spelling of 21802291 in words is "twenty-one million, eight hundred two thousand, two hundred ninety-one".