21203004531 has 4 divisors (see below), whose sum is σ = 28270672712. Its totient is φ = 14135336352.

The previous prime is 21203004527. The next prime is 21203004551. The reversal of 21203004531 is 13540030212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21203004531 - 2² = 21203004527 is a prime.

It is a super-2 number, since 2×21203004531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21203004498 and 21203004507.

It is not an unprimeable number, because it can be changed into a prime (21203004551) 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, 3533834086 + ... + 3533834091.

It is an arithmetic number, because the mean of its divisors is an integer number (7067668178).

Almost surely, 2^21203004531 is an apocalyptic number.

21203004531 is a deficient number, since it is larger than the sum of its proper divisors (7067668181).

21203004531 is an equidigital number, since it uses as much as digits as its factorization.

21203004531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7067668180.

The product of its (nonzero) digits is 720, while the sum is 21.

Adding to 21203004531 its reverse (13540030212), we get a palindrome (34743034743).

The spelling of 21203004531 in words is "twenty-one billion, two hundred three million, four thousand, five hundred thirty-one".