21320310042 has 24 divisors (see below), whose sum is σ = 47320689780. Its totient is φ = 6933433920.

The previous prime is 21320310041. The next prime is 21320310043. The reversal of 21320310042 is 24001302312.

It is an interprime number because it is at equal distance from previous prime (21320310041) and next prime (21320310043).

It can be written as a sum of positive squares in 2 ways, for example, as 16708406121 + 4611903921 = 129261^2 + 67911^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21320309997 and 21320310024.

It is not an unprimeable number, because it can be changed into a prime (21320310041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14443917 + ... + 14445392.

Almost surely, 2^21320310042 is an apocalyptic number.

21320310042 is an abundant number, since it is smaller than the sum of its proper divisors (26000379738).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21320310042 is a wasteful number, since it uses less digits than its factorization.

21320310042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28889358 (or 28889355 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21320310042 its reverse (24001302312), we get a palindrome (45321612354).

The spelling of 21320310042 in words is "twenty-one billion, three hundred twenty million, three hundred ten thousand, forty-two".