21531200431 has 4 divisors (see below), whose sum is σ = 23187446632. Its totient is φ = 19874954232.

The previous prime is 21531200419. The next prime is 21531200437. The reversal of 21531200431 is 13400213512.

It is a happy number.

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 21531200431 - 2¹⁵ = 21531167663 is a prime.

It is a super-2 number, since 2×21531200431² (a number of 21 digits) 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 (21531200437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 828123081 + ... + 828123106.

It is an arithmetic number, because the mean of its divisors is an integer number (5796861658).

Almost surely, 2^21531200431 is an apocalyptic number.

21531200431 is a deficient number, since it is larger than the sum of its proper divisors (1656246201).

21531200431 is a wasteful number, since it uses less digits than its factorization.

21531200431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1656246200.

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 21531200431 its reverse (13400213512), we get a palindrome (34931413943).

The spelling of 21531200431 in words is "twenty-one billion, five hundred thirty-one million, two hundred thousand, four hundred thirty-one".