21016420043 has 4 divisors (see below), whose sum is σ = 21019649448. Its totient is φ = 21013190640.

The previous prime is 21016420027. The next prime is 21016420063. The reversal of 21016420043 is 34002461012.

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 21016420043 - 2⁴ = 21016420027 is a prime.

It is a super-2 number, since 2×21016420043² (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 (21016420063) 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, 1604921 + ... + 1617962.

It is an arithmetic number, because the mean of its divisors is an integer number (5254912362).

Almost surely, 2^21016420043 is an apocalyptic number.

21016420043 is a deficient number, since it is larger than the sum of its proper divisors (3229405).

21016420043 is an equidigital number, since it uses as much as digits as its factorization.

21016420043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3229404.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21016420043 its reverse (34002461012), we get a palindrome (55018881055).

The spelling of 21016420043 in words is "twenty-one billion, sixteen million, four hundred twenty thousand, forty-three".