21802149 has 8 divisors (see below), whose sum is σ = 32299520. Its totient is φ = 14534748.

The previous prime is 21802141. The next prime is 21802159. The reversal of 21802149 is 94120812.

It is not a de Polignac number, because 21802149 - 2³ = 21802141 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 807487 = 21802149 / (2 + 1 + 8 + 0 + 2 + 1 + 4 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21802141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 403717 + ... + 403770.

It is an arithmetic number, because the mean of its divisors is an integer number (4037440).

Almost surely, 2^21802149 is an apocalyptic number.

It is an amenable number.

21802149 is a deficient number, since it is larger than the sum of its proper divisors (10497371).

21802149 is an equidigital number, since it uses as much as digits as its factorization.

21802149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807496 (or 807490 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21802149 is about 4669.2771389156. The cubic root of 21802149 is about 279.3614231500.

It can be divided in two parts, 2 and 1802149, that added together give a triangular number (1802151 = T₁₈₉₈).

The spelling of 21802149 in words is "twenty-one million, eight hundred two thousand, one hundred forty-nine".