21103031 has 4 divisors (see below), whose sum is σ = 21129864. Its totient is φ = 21076200.

The previous prime is 21103021. The next prime is 21103051. The reversal of 21103031 is 13030112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21103031 - 2¹⁸ = 20840887 is a prime.

It is a super-2 number, since 2×21103031² = 890675834773922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12200 + ... + 13821.

It is an arithmetic number, because the mean of its divisors is an integer number (5282466).

Almost surely, 2^21103031 is an apocalyptic number.

21103031 is a deficient number, since it is larger than the sum of its proper divisors (26833).

21103031 is an equidigital number, since it uses as much as digits as its factorization.

21103031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26832.

The product of its (nonzero) digits is 18, while the sum is 11.

The square root of 21103031 is about 4593.8035439056. The cubic root of 21103031 is about 276.3428797112.

Adding to 21103031 its reverse (13030112), we get a palindrome (34133143).

The spelling of 21103031 in words is "twenty-one million, one hundred three thousand, thirty-one".