28427723781 has 4 divisors (see below), whose sum is σ = 37903631712. Its totient is φ = 18951815852.

The previous prime is 28427723777. The next prime is 28427723809. The reversal of 28427723781 is 18732772482.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28427723781 - 2² = 28427723777 is a prime.

It is a super-2 number, since 2×28427723781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28427723761) 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, 4737953961 + ... + 4737953966.

It is an arithmetic number, because the mean of its divisors is an integer number (9475907928).

Almost surely, 2^28427723781 is an apocalyptic number.

It is an amenable number.

28427723781 is a deficient number, since it is larger than the sum of its proper divisors (9475907931).

28427723781 is an equidigital number, since it uses as much as digits as its factorization.

28427723781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9475907930.

The product of its digits is 2107392, while the sum is 51.

The spelling of 28427723781 in words is "twenty-eight billion, four hundred twenty-seven million, seven hundred twenty-three thousand, seven hundred eighty-one".