21021031043 has 4 divisors (see below), whose sum is σ = 21049323888. Its totient is φ = 20992738200.

The previous prime is 21021031037. The next prime is 21021031069. The reversal of 21021031043 is 34013012012.

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 21021031043 - 2¹² = 21021026947 is a prime.

It is a super-2 number, since 2×21021031043² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021091043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14145308 + ... + 14146793.

It is an arithmetic number, because the mean of its divisors is an integer number (5262330972).

Almost surely, 2^21021031043 is an apocalyptic number.

21021031043 is a deficient number, since it is larger than the sum of its proper divisors (28292845).

21021031043 is an equidigital number, since it uses as much as digits as its factorization.

21021031043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28292844.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21021031043 its reverse (34013012012), we get a palindrome (55034043055).

The spelling of 21021031043 in words is "twenty-one billion, twenty-one million, thirty-one thousand, forty-three".