21185801 has 8 divisors (see below), whose sum is σ = 26074944. Its totient is φ = 16762320.

The previous prime is 21185789. The next prime is 21185821. The reversal of 21185801 is 10858112.

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

It is a cyclic number.

It is not a de Polignac number, because 21185801 - 2¹⁴ = 21169417 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21185821) 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, 116315 + ... + 116496.

It is an arithmetic number, because the mean of its divisors is an integer number (3259368).

Almost surely, 2^21185801 is an apocalyptic number.

It is an amenable number.

21185801 is a deficient number, since it is larger than the sum of its proper divisors (4889143).

21185801 is a wasteful number, since it uses less digits than its factorization.

21185801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232831.

The product of its (nonzero) digits is 640, while the sum is 26.

The square root of 21185801 is about 4602.8036021538. The cubic root of 21185801 is about 276.7036977255.

It can be divided in two parts, 21 and 185801, that multiplied together give a triangular number (3901821 = T₂₇₉₃).

The spelling of 21185801 in words is "twenty-one million, one hundred eighty-five thousand, eight hundred one".