21798131 has 8 divisors (see below), whose sum is σ = 23320080. Its totient is φ = 20302848.

The previous prime is 21798113. The next prime is 21798137. The reversal of 21798131 is 13189712.

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 21798131 - 2⁶ = 21798067 is a prime.

It is a super-2 number, since 2×21798131² = 950317030186322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21798137) 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, 4961 + ... + 8258.

It is an arithmetic number, because the mean of its divisors is an integer number (2915010).

Almost surely, 2^21798131 is an apocalyptic number.

21798131 is a deficient number, since it is larger than the sum of its proper divisors (1521949).

21798131 is a wasteful number, since it uses less digits than its factorization.

21798131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13333.

The product of its digits is 3024, while the sum is 32.

The square root of 21798131 is about 4668.8468597717. The cubic root of 21798131 is about 279.3442605733.

The spelling of 21798131 in words is "twenty-one million, seven hundred ninety-eight thousand, one hundred thirty-one".