21748978508 has 12 divisors (see below), whose sum is σ = 38294214840. Its totient is φ = 10807774272.

The previous prime is 21748978507. The next prime is 21748978519. The reversal of 21748978508 is 80587984712.

It is a super-2 number, since 2×21748978508² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21748978507) 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, 16678013 + ... + 16679316.

It is an arithmetic number, because the mean of its divisors is an integer number (3191184570).

Almost surely, 2^21748978508 is an apocalyptic number.

It is an amenable number.

21748978508 is a deficient number, since it is larger than the sum of its proper divisors (16545236332).

21748978508 is a wasteful number, since it uses less digits than its factorization.

21748978508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33357496 (or 33357494 counting only the distinct ones).

The product of its (nonzero) digits is 9031680, while the sum is 59.

The spelling of 21748978508 in words is "twenty-one billion, seven hundred forty-eight million, nine hundred seventy-eight thousand, five hundred eight".