28400691987 has 40 divisors (see below), whose sum is σ = 43515394560. Its totient is φ = 18449590320.

The previous prime is 28400691971. The next prime is 28400692007. The reversal of 28400691987 is 78919600482.

It is not a de Polignac number, because 28400691987 - 2⁴ = 28400691971 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28400691947) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1491714 + ... + 1510632.

It is an arithmetic number, because the mean of its divisors is an integer number (1087884864).

Almost surely, 2^28400691987 is an apocalyptic number.

28400691987 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

28400691987 is a deficient number, since it is larger than the sum of its proper divisors (15114702573).

28400691987 is a wasteful number, since it uses less digits than its factorization.

28400691987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19405 (or 19396 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 54.

The spelling of 28400691987 in words is "twenty-eight billion, four hundred million, six hundred ninety-one thousand, nine hundred eighty-seven".