21855031 has 8 divisors (see below), whose sum is σ = 24611328. Its totient is φ = 19227000.

The previous prime is 21855017. The next prime is 21855061. The reversal of 21855031 is 13055812.

It is a happy number.

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 21855031 - 2¹⁷ = 21723959 is a prime.

It is a super-2 number, since 2×21855031² = 955284760021922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21854987 and 21855005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855011) 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, 31705 + ... + 32386.

It is an arithmetic number, because the mean of its divisors is an integer number (3076416).

Almost surely, 2^21855031 is an apocalyptic number.

21855031 is a deficient number, since it is larger than the sum of its proper divisors (2756297).

21855031 is a wasteful number, since it uses less digits than its factorization.

21855031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64133.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 21855031 is about 4674.9364701566. The cubic root of 21855031 is about 279.5871082804.

The spelling of 21855031 in words is "twenty-one million, eight hundred fifty-five thousand, thirty-one".