21871031 has 8 divisors (see below), whose sum is σ = 26918304. Its totient is φ = 17304480.

The previous prime is 21870997. The next prime is 21871039. The reversal of 21871031 is 13017812.

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 21871031 - 2⁶ = 21870967 is a prime.

It is a super-2 number, since 2×21871031² = 956683994005922, which contains 22 as substring.

It is a plaindrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 21870988 and 21871006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871039) 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, 120080 + ... + 120261.

It is an arithmetic number, because the mean of its divisors is an integer number (3364788).

Almost surely, 2^21871031 is an apocalyptic number.

21871031 is a deficient number, since it is larger than the sum of its proper divisors (5047273).

21871031 is a wasteful number, since it uses less digits than its factorization.

21871031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240361.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21871031 is about 4676.6474102716. The cubic root of 21871031 is about 279.6553199204.

Adding to 21871031 its reverse (13017812), we get a palindrome (34888843).

The spelling of 21871031 in words is "twenty-one million, eight hundred seventy-one thousand, thirty-one".