21798081 has 12 divisors (see below), whose sum is σ = 32020560. Its totient is φ = 14285400.

The previous prime is 21798067. The next prime is 21798107. The reversal of 21798081 is 18089712.

It is not a de Polignac number, because 21798081 - 2⁶ = 21798017 is a prime.

It is a super-2 number, since 2×21798081² = 950312670565122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21798001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19995 + ... + 21056.

It is an arithmetic number, because the mean of its divisors is an integer number (2668380).

Almost surely, 2^21798081 is an apocalyptic number.

It is an amenable number.

21798081 is a deficient number, since it is larger than the sum of its proper divisors (10222479).

21798081 is a wasteful number, since it uses less digits than its factorization.

21798081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41116 (or 41113 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 21798081 is about 4668.8415051274. The cubic root of 21798081 is about 279.3440469889.

The spelling of 21798081 in words is "twenty-one million, seven hundred ninety-eight thousand, eighty-one".