21802151 has 4 divisors (see below), whose sum is σ = 24916752. Its totient is φ = 18687552.

The previous prime is 21802141. The next prime is 21802159. The reversal of 21802151 is 15120812.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21802151 - 2¹⁴ = 21785767 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21802159) 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 3 ways as a sum of consecutive naturals, for example, 1557290 + ... + 1557303.

It is an arithmetic number, because the mean of its divisors is an integer number (6229188).

Almost surely, 2^21802151 is an apocalyptic number.

21802151 is a deficient number, since it is larger than the sum of its proper divisors (3114601).

21802151 is an equidigital number, since it uses as much as digits as its factorization.

21802151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3114600.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 21802151 is about 4669.2773530815. The cubic root of 21802151 is about 279.3614316923.

Adding to 21802151 its reverse (15120812), we get a palindrome (36922963).

The spelling of 21802151 in words is "twenty-one million, eight hundred two thousand, one hundred fifty-one".