21311019973 has 4 divisors (see below), whose sum is σ = 21312031648. Its totient is φ = 21310008300.

The previous prime is 21311019971. The next prime is 21311019997. The reversal of 21311019973 is 37991011312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21311019973 - 2¹ = 21311019971 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311019971) 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, 473553 + ... + 516598.

It is an arithmetic number, because the mean of its divisors is an integer number (5328007912).

Almost surely, 2^21311019973 is an apocalyptic number.

It is an amenable number.

21311019973 is a deficient number, since it is larger than the sum of its proper divisors (1011675).

21311019973 is an equidigital number, since it uses as much as digits as its factorization.

21311019973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011674.

The product of its (nonzero) digits is 10206, while the sum is 37.

The spelling of 21311019973 in words is "twenty-one billion, three hundred eleven million, nineteen thousand, nine hundred seventy-three".