128697840 has 120 divisors (see below), whose sum is σ = 443983488. Its totient is φ = 33384960.

The previous prime is 128697823. The next prime is 128697851. The reversal of 128697840 is 48796821.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24225 + ... + 29055.

Almost surely, 2^128697840 is an apocalyptic number.

128697840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 128697840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (221991744).

128697840 is an abundant number, since it is smaller than the sum of its proper divisors (315285648).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

128697840 is a wasteful number, since it uses less digits than its factorization.

128697840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4887 (or 4878 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 128697840 is about 11344.5070408546. The cubic root of 128697840 is about 504.8826182103.

The spelling of 128697840 in words is "one hundred twenty-eight million, six hundred ninety-seven thousand, eight hundred forty".