21165943829 has 4 divisors (see below), whose sum is σ = 21166971840. Its totient is φ = 21164915820.

The previous prime is 21165943787. The next prime is 21165943831. The reversal of 21165943829 is 92834956112.

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 a de Polignac number, because none of the positive numbers 2^k-21165943829 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185943829) 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, 482477 + ... + 524514.

It is an arithmetic number, because the mean of its divisors is an integer number (5291742960).

Almost surely, 2^21165943829 is an apocalyptic number.

It is an amenable number.

21165943829 is a deficient number, since it is larger than the sum of its proper divisors (1028011).

21165943829 is a wasteful number, since it uses less digits than its factorization.

21165943829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1028010.

The product of its digits is 933120, while the sum is 50.

The spelling of 21165943829 in words is "twenty-one billion, one hundred sixty-five million, nine hundred forty-three thousand, eight hundred twenty-nine".