21533042420 has 12 divisors (see below), whose sum is σ = 45219389124. Its totient is φ = 8613216960.

The previous prime is 21533042417. The next prime is 21533042423. The reversal of 21533042420 is 2424033512.

It is an interprime number because it is at equal distance from previous prime (21533042417) and next prime (21533042423).

It can be written as a sum of positive squares in 2 ways, for example, as 10029621904 + 11503420516 = 100148^2 + 107254^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21533042420.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533042423) 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, 538326041 + ... + 538326080.

It is an arithmetic number, because the mean of its divisors is an integer number (3768282427).

Almost surely, 2^21533042420 is an apocalyptic number.

21533042420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21533042420 is an abundant number, since it is smaller than the sum of its proper divisors (23686346704).

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

21533042420 is a wasteful number, since it uses less digits than its factorization.

21533042420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1076652130 (or 1076652128 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 26.

Adding to 21533042420 its reverse (2424033512), we get a palindrome (23957075932).

The spelling of 21533042420 in words is "twenty-one billion, five hundred thirty-three million, forty-two thousand, four hundred twenty".