21550991829 has 4 divisors (see below), whose sum is σ = 28734655776. Its totient is φ = 14367327884.

The previous prime is 21550991809. The next prime is 21550991863. The reversal of 21550991829 is 92819905512.

It is a happy number.

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 21550991829 - 2⁷ = 21550991701 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550991809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3591831969 + ... + 3591831974.

It is an arithmetic number, because the mean of its divisors is an integer number (7183663944).

Almost surely, 2^21550991829 is an apocalyptic number.

It is an amenable number.

21550991829 is a deficient number, since it is larger than the sum of its proper divisors (7183663947).

21550991829 is an equidigital number, since it uses as much as digits as its factorization.

21550991829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7183663946.

The product of its (nonzero) digits is 583200, while the sum is 51.

The spelling of 21550991829 in words is "twenty-one billion, five hundred fifty million, nine hundred ninety-one thousand, eight hundred twenty-nine".