21801245 has 8 divisors (see below), whose sum is σ = 26214840. Its totient is φ = 17405440.

The previous prime is 21801211. The next prime is 21801271. The reversal of 21801245 is 54210812.

It can be written as a sum of positive squares in 4 ways, for example, as 2256004 + 19545241 = 1502^2 + 4421^2 .

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

It is not a de Polignac number, because 21801245 - 2⁶ = 21801181 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21801245.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1580 + ... + 6789.

It is an arithmetic number, because the mean of its divisors is an integer number (3276855).

Almost surely, 2^21801245 is an apocalyptic number.

It is an amenable number.

21801245 is a deficient number, since it is larger than the sum of its proper divisors (4413595).

21801245 is an equidigital number, since it uses as much as digits as its factorization.

21801245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8895.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21801245 is about 4669.1803349196. The cubic root of 21801245 is about 279.3575619676.

The spelling of 21801245 in words is "twenty-one million, eight hundred one thousand, two hundred forty-five".