21509533042 has 8 divisors (see below), whose sum is σ = 32290814556. Its totient is φ = 10745928192.

The previous prime is 21509533021. The next prime is 21509533043. The reversal of 21509533042 is 24033590512.

It can be written as a sum of positive squares in 2 ways, for example, as 21508862281 + 670761 = 146659^2 + 819^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21509532989 and 21509533007.

It is not an unprimeable number, because it can be changed into a prime (21509533043) 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, 4416123 + ... + 4420990.

Almost surely, 2^21509533042 is an apocalyptic number.

21509533042 is a deficient number, since it is larger than the sum of its proper divisors (10781281514).

21509533042 is a wasteful number, since it uses less digits than its factorization.

21509533042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8838332.

The product of its (nonzero) digits is 32400, while the sum is 34.

The spelling of 21509533042 in words is "twenty-one billion, five hundred nine million, five hundred thirty-three thousand, forty-two".