21531051421 has 8 divisors (see below), whose sum is σ = 24298365600. Its totient is φ = 18898728240.

The previous prime is 21531051413. The next prime is 21531051439. The reversal of 21531051421 is 12415013512.

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

It is a cyclic number.

It is not a de Polignac number, because 21531051421 - 2³ = 21531051413 is a prime.

It is a super-3 number, since 3×21531051421³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531051481) 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 7 ways as a sum of consecutive naturals, for example, 33747411 + ... + 33748048.

It is an arithmetic number, because the mean of its divisors is an integer number (3037295700).

Almost surely, 2^21531051421 is an apocalyptic number.

It is an amenable number.

21531051421 is a deficient number, since it is larger than the sum of its proper divisors (2767314179).

21531051421 is a wasteful number, since it uses less digits than its factorization.

21531051421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67495499.

The product of its (nonzero) digits is 1200, while the sum is 25.

Adding to 21531051421 its reverse (12415013512), we get a palindrome (33946064933).

The spelling of 21531051421 in words is "twenty-one billion, five hundred thirty-one million, fifty-one thousand, four hundred twenty-one".