128856731 has 2 divisors, whose sum is σ = 128856732. Its totient is φ = 128856730.

The previous prime is 128856703. The next prime is 128856743. The reversal of 128856731 is 137658821.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128856731 is a prime.

It is a super-2 number, since 2×128856731² = 33208114248012722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (128856701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64428365 + 64428366.

It is an arithmetic number, because the mean of its divisors is an integer number (64428366).

Almost surely, 2^128856731 is an apocalyptic number.

128856731 is a deficient number, since it is larger than the sum of its proper divisors (1).

128856731 is an equidigital number, since it uses as much as digits as its factorization.

128856731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 41.

The square root of 128856731 is about 11351.5078734061. The cubic root of 128856731 is about 505.0903096339.

The spelling of 128856731 in words is "one hundred twenty-eight million, eight hundred fifty-six thousand, seven hundred thirty-one".