21531820673 has 8 divisors (see below), whose sum is σ = 23501599200. Its totient is φ = 19564098880.

The previous prime is 21531820649. The next prime is 21531820693. The reversal of 21531820673 is 37602813512.

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 21531820673 - 2⁸ = 21531820417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21531820603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 492248 + ... + 534201.

It is an arithmetic number, because the mean of its divisors is an integer number (2937699900).

Almost surely, 2^21531820673 is an apocalyptic number.

It is an amenable number.

21531820673 is a deficient number, since it is larger than the sum of its proper divisors (1969778527).

21531820673 is a wasteful number, since it uses less digits than its factorization.

21531820673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1028367.

The product of its (nonzero) digits is 60480, while the sum is 38.

The spelling of 21531820673 in words is "twenty-one billion, five hundred thirty-one million, eight hundred twenty thousand, six hundred seventy-three".