21220031 has 8 divisors (see below), whose sum is σ = 24310944. Its totient is φ = 18144000.

The previous prime is 21220019. The next prime is 21220103. The reversal of 21220031 is 13002212.

It is a happy number.

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

It is not a de Polignac number, because 21220031 - 2¹⁰ = 21219007 is a prime.

It is a super-2 number, since 2×21220031² = 900579431281922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21219994 and 21220021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220231) 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, 470 + ... + 6531.

It is an arithmetic number, because the mean of its divisors is an integer number (3038868).

Almost surely, 2^21220031 is an apocalyptic number.

21220031 is a deficient number, since it is larger than the sum of its proper divisors (3090913).

21220031 is an equidigital number, since it uses as much as digits as its factorization.

21220031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7441.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21220031 is about 4606.5204873093. The cubic root of 21220031 is about 276.8526413672.

Adding to 21220031 its reverse (13002212), we get a palindrome (34222243).

The spelling of 21220031 in words is "twenty-one million, two hundred twenty thousand, thirty-one".