21509277993 has 18 divisors (see below), whose sum is σ = 36141440634. Its totient is φ = 12291015744.

The previous prime is 21509277961. The next prime is 21509278027. The reversal of 21509277993 is 39977290512.

21509277993 is a `hidden beast` number, since 21 + 509 + 27 + 7 + 9 + 93 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16668875664 + 4840402329 = 129108^2 + 69573^2 .

It is not a de Polignac number, because 21509277993 - 2⁵ = 21509277961 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21509277943) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 24386496 + ... + 24387377.

It is an arithmetic number, because the mean of its divisors is an integer number (2007857813).

Almost surely, 2^21509277993 is an apocalyptic number.

It is an amenable number.

21509277993 is a deficient number, since it is larger than the sum of its proper divisors (14632162641).

21509277993 is a wasteful number, since it uses less digits than its factorization.

21509277993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48773893 (or 48773883 counting only the distinct ones).

The product of its (nonzero) digits is 2143260, while the sum is 54.

The spelling of 21509277993 in words is "twenty-one billion, five hundred nine million, two hundred seventy-seven thousand, nine hundred ninety-three".