21821768658 has 32 divisors (see below), whose sum is σ = 48551414400. Its totient is φ = 7265133648.

The previous prime is 21821768653. The next prime is 21821768659. The reversal of 21821768658 is 85686712812.

It is a super-2 number, since 2×21821768658² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (21821768653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 198966 + ... + 288497.

It is an arithmetic number, because the mean of its divisors is an integer number (1517231700).

Almost surely, 2^21821768658 is an apocalyptic number.

21821768658 is an abundant number, since it is smaller than the sum of its proper divisors (26729645742).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21821768658 is a wasteful number, since it uses less digits than its factorization.

21821768658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488303 (or 488297 counting only the distinct ones).

The product of its digits is 2580480, while the sum is 54.

The spelling of 21821768658 in words is "twenty-one billion, eight hundred twenty-one million, seven hundred sixty-eight thousand, six hundred fifty-eight".