21500489197 has 4 divisors (see below), whose sum is σ = 23455079136. Its totient is φ = 19545899260.

The previous prime is 21500489147. The next prime is 21500489207. The reversal of 21500489197 is 79198400512.

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 21500489197 - 2²³ = 21492100589 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 (21500489117) 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, 977294953 + ... + 977294974.

It is an arithmetic number, because the mean of its divisors is an integer number (5863769784).

Almost surely, 2^21500489197 is an apocalyptic number.

It is an amenable number.

21500489197 is a deficient number, since it is larger than the sum of its proper divisors (1954589939).

21500489197 is a wasteful number, since it uses less digits than its factorization.

21500489197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1954589938.

The product of its (nonzero) digits is 181440, while the sum is 46.

The spelling of 21500489197 in words is "twenty-one billion, five hundred million, four hundred eighty-nine thousand, one hundred ninety-seven".