129561408 has 84 divisors (see below), whose sum is σ = 380073408. Its totient is φ = 42174720.

The previous prime is 129561407. The next prime is 129561409. The reversal of 129561408 is 804165921.

It is an interprime number because it is at equal distance from previous prime (129561407) and next prime (129561409).

It is a Smith number, since the sum of its digits (36) 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 (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129561407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22153 + ... + 27383.

Almost surely, 2^129561408 is an apocalyptic number.

129561408 is a gapful number since it is divisible by the number (18) 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 129561408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (190036704).

129561408 is an abundant number, since it is smaller than the sum of its proper divisors (250512000).

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

129561408 is a wasteful number, since it uses less digits than its factorization.

129561408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5292 (or 5279 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 129561408 is about 11382.5044695796. The cubic root of 129561408 is about 506.0093630934.

The spelling of 129561408 in words is "one hundred twenty-nine million, five hundred sixty-one thousand, four hundred eight".