28651391 has 4 divisors (see below), whose sum is σ = 29639400. Its totient is φ = 27663384.

The previous prime is 28651387. The next prime is 28651393. The reversal of 28651391 is 19315682.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28651391 - 2² = 28651387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28651393) 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, 493961 + ... + 494018.

It is an arithmetic number, because the mean of its divisors is an integer number (7409850).

Almost surely, 2^28651391 is an apocalyptic number.

28651391 is a deficient number, since it is larger than the sum of its proper divisors (988009).

28651391 is an equidigital number, since it uses as much as digits as its factorization.

28651391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988008.

The product of its digits is 12960, while the sum is 35.

The square root of 28651391 is about 5352.6994124460. The cubic root of 28651391 is about 305.9956390795.

The spelling of 28651391 in words is "twenty-eight million, six hundred fifty-one thousand, three hundred ninety-one".