21520413431 has 8 divisors (see below), whose sum is σ = 23480531328. Its totient is φ = 19560915000.

The previous prime is 21520413391. The next prime is 21520413451. The reversal of 21520413431 is 13431402512.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21520413431 - 2³⁰ = 20446671607 is a prime.

It is a super-2 number, since 2×21520413431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21520413431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520413451) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80675 + ... + 222596.

It is an arithmetic number, because the mean of its divisors is an integer number (2935066416).

Almost surely, 2^21520413431 is an apocalyptic number.

21520413431 is a deficient number, since it is larger than the sum of its proper divisors (1960117897).

21520413431 is a wasteful number, since it uses less digits than its factorization.

21520413431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309733.

The product of its (nonzero) digits is 2880, while the sum is 26.

Adding to 21520413431 its reverse (13431402512), we get a palindrome (34951815943).

The spelling of 21520413431 in words is "twenty-one billion, five hundred twenty million, four hundred thirteen thousand, four hundred thirty-one".