128521707 has 16 divisors (see below), whose sum is σ = 177600000. Its totient is φ = 82573344.

The previous prime is 128521699. The next prime is 128521709. The reversal of 128521707 is 707125821.

It is not a de Polignac number, because 128521707 - 2³ = 128521699 is a prime.

It is not an unprimeable number, because it can be changed into a prime (128521709) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 63294 + ... + 65292.

It is an arithmetic number, because the mean of its divisors is an integer number (11100000).

Almost surely, 2^128521707 is an apocalyptic number.

128521707 is a deficient number, since it is larger than the sum of its proper divisors (49078293).

128521707 is a wasteful number, since it uses less digits than its factorization.

128521707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2770.

The product of its (nonzero) digits is 7840, while the sum is 33.

The square root of 128521707 is about 11336.7414630484. The cubic root of 128521707 is about 504.6521893528.

The spelling of 128521707 in words is "one hundred twenty-eight million, five hundred twenty-one thousand, seven hundred seven".