21820763644 has 12 divisors (see below), whose sum is σ = 40432591584. Its totient is φ = 10268594624.

The previous prime is 21820763641. The next prime is 21820763647. The reversal of 21820763644 is 44636702812.

It is an interprime number because it is at equal distance from previous prime (21820763641) and next prime (21820763647).

It is a super-2 number, since 2×21820763644² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21820763644.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820763641) 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, 160446724 + ... + 160446859.

It is an arithmetic number, because the mean of its divisors is an integer number (3369382632).

Almost surely, 2^21820763644 is an apocalyptic number.

It is an amenable number.

21820763644 is a deficient number, since it is larger than the sum of its proper divisors (18611827940).

21820763644 is a wasteful number, since it uses less digits than its factorization.

21820763644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320893604 (or 320893602 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 43.

The spelling of 21820763644 in words is "twenty-one billion, eight hundred twenty million, seven hundred sixty-three thousand, six hundred forty-four".