21763730821 has 4 divisors (see below), whose sum is σ = 24872835232. Its totient is φ = 18654626412.

The previous prime is 21763730797. The next prime is 21763730851. The reversal of 21763730821 is 12803736712.

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 21763730821 - 2¹⁵ = 21763698053 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21763730851) 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, 1554552195 + ... + 1554552208.

It is an arithmetic number, because the mean of its divisors is an integer number (6218208808).

Almost surely, 2^21763730821 is an apocalyptic number.

It is an amenable number.

21763730821 is a deficient number, since it is larger than the sum of its proper divisors (3109104411).

21763730821 is an equidigital number, since it uses as much as digits as its factorization.

21763730821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3109104410.

The product of its (nonzero) digits is 84672, while the sum is 40.

The spelling of 21763730821 in words is "twenty-one billion, seven hundred sixty-three million, seven hundred thirty thousand, eight hundred twenty-one".