21550403507 has 4 divisors (see below), whose sum is σ = 21714910536. Its totient is φ = 21385896480.

The previous prime is 21550403503. The next prime is 21550403533. The reversal of 21550403507 is 70530405512.

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

It is a cyclic number.

It is not a de Polignac number, because 21550403507 - 2² = 21550403503 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21550403503) 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, 82253318 + ... + 82253579.

It is an arithmetic number, because the mean of its divisors is an integer number (5428727634).

Almost surely, 2^21550403507 is an apocalyptic number.

21550403507 is a deficient number, since it is larger than the sum of its proper divisors (164507029).

21550403507 is a wasteful number, since it uses less digits than its factorization.

21550403507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164507028.

The product of its (nonzero) digits is 21000, while the sum is 32.

The spelling of 21550403507 in words is "twenty-one billion, five hundred fifty million, four hundred three thousand, five hundred seven".