21539923099 has 4 divisors (see below), whose sum is σ = 22234759360. Its totient is φ = 20845086840.

The previous prime is 21539923091. The next prime is 21539923103. The reversal of 21539923099 is 99032993512.

It is a happy number.

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 21539923099 - 2³ = 21539923091 is a prime.

It is a super-2 number, since 2×21539923099² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21539923091) 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, 347418084 + ... + 347418145.

It is an arithmetic number, because the mean of its divisors is an integer number (5558689840).

Almost surely, 2^21539923099 is an apocalyptic number.

21539923099 is a deficient number, since it is larger than the sum of its proper divisors (694836261).

21539923099 is an equidigital number, since it uses as much as digits as its factorization.

21539923099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 694836260.

The product of its (nonzero) digits is 1180980, while the sum is 52.

The spelling of 21539923099 in words is "twenty-one billion, five hundred thirty-nine million, nine hundred twenty-three thousand, ninety-nine".