128401631 has 2 divisors, whose sum is σ = 128401632. Its totient is φ = 128401630.

The previous prime is 128401613. The next prime is 128401643. The reversal of 128401631 is 136104821.

Together with previous prime (128401613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is an emirp because it is prime and its reverse (136104821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128401631 - 2²⁶ = 61292767 is a prime.

It is a super-2 number, since 2×128401631² = 32973957686920322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128401631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128401661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64200815 + 64200816.

It is an arithmetic number, because the mean of its divisors is an integer number (64200816).

Almost surely, 2^128401631 is an apocalyptic number.

128401631 is a deficient number, since it is larger than the sum of its proper divisors (1).

128401631 is an equidigital number, since it uses as much as digits as its factorization.

128401631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 128401631 is about 11331.4443474784. Note that the first 3 decimals coincide. The cubic root of 128401631 is about 504.4949772652.

The spelling of 128401631 in words is "one hundred twenty-eight million, four hundred one thousand, six hundred thirty-one".