21006562708 has 18 divisors (see below), whose sum is σ = 37679987198. Its totient is φ = 10247100480.

The previous prime is 21006562691. The next prime is 21006562727. The reversal of 21006562708 is 80726560012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 5151219984 + 15855342724 = 71772^2 + 125918^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1555335 + ... + 1568782.

Almost surely, 2^21006562708 is an apocalyptic number.

It is an amenable number.

21006562708 is a deficient number, since it is larger than the sum of its proper divisors (16673424490).

21006562708 is a wasteful number, since it uses less digits than its factorization.

21006562708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3124203 (or 3124160 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 37.

The spelling of 21006562708 in words is "twenty-one billion, six million, five hundred sixty-two thousand, seven hundred eight".