27781528021 has 16 divisors (see below), whose sum is σ = 31033769536. Its totient is φ = 24704942976.

The previous prime is 27781528007. The next prime is 27781528037. The reversal of 27781528021 is 12082518772.

It is a cyclic number.

It is not a de Polignac number, because 27781528021 - 2¹¹ = 27781525973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27781538021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 299595 + ... + 381208.

It is an arithmetic number, because the mean of its divisors is an integer number (1939610596).

Almost surely, 2^27781528021 is an apocalyptic number.

It is an amenable number.

27781528021 is a deficient number, since it is larger than the sum of its proper divisors (3252241515).

27781528021 is a wasteful number, since it uses less digits than its factorization.

27781528021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680932.

The product of its (nonzero) digits is 125440, while the sum is 43.

The spelling of 27781528021 in words is "twenty-seven billion, seven hundred eighty-one million, five hundred twenty-eight thousand, twenty-one".