21985507688 has 8 divisors (see below), whose sum is σ = 41222826930. Its totient is φ = 10992753840.

The previous prime is 21985507679. The next prime is 21985507729. The reversal of 21985507688 is 88670558912.

It can be written as a sum of positive squares in only one way, i.e., 21106859524 + 878648164 = 145282^2 + 29642^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1374094223 + ... + 1374094238.

Almost surely, 2^21985507688 is an apocalyptic number.

It is an amenable number.

21985507688 is a deficient number, since it is larger than the sum of its proper divisors (19237319242).

21985507688 is a wasteful number, since it uses less digits than its factorization.

21985507688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2748188467 (or 2748188463 counting only the distinct ones).

The product of its (nonzero) digits is 9676800, while the sum is 59.

The spelling of 21985507688 in words is "twenty-one billion, nine hundred eighty-five million, five hundred seven thousand, six hundred eighty-eight".