21503535421 has 4 divisors (see below), whose sum is σ = 22084712092. Its totient is φ = 20922358752.

The previous prime is 21503535413. The next prime is 21503535439. The reversal of 21503535421 is 12453530512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18882607396 + 2620928025 = 137414^2 + 51195^2 .

It is a cyclic number.

It is not a de Polignac number, because 21503535421 - 2³ = 21503535413 is a prime.

It is a super-3 number, since 3×21503535421³ (a number of 32 digits) contains 333 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 (21503533421) 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, 290588280 + ... + 290588353.

It is an arithmetic number, because the mean of its divisors is an integer number (5521178023).

Almost surely, 2^21503535421 is an apocalyptic number.

It is an amenable number.

21503535421 is a deficient number, since it is larger than the sum of its proper divisors (581176671).

21503535421 is an equidigital number, since it uses as much as digits as its factorization.

21503535421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581176670.

The product of its (nonzero) digits is 18000, while the sum is 31.

The spelling of 21503535421 in words is "twenty-one billion, five hundred three million, five hundred thirty-five thousand, four hundred twenty-one".