29681640 has 80 divisors (see below), whose sum is σ = 99774180. Its totient is φ = 7914240.

The previous prime is 29681633. The next prime is 29681651. The reversal of 29681640 is 4618692.

29681640 is a `hidden beast` number, since 2 + 9 + 6 + 8 + 1 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 28965924 + 715716 = 5382^2 + 846^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 29681595 and 29681604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1341 + ... + 7820.

Almost surely, 2^29681640 is an apocalyptic number.

29681640 is a gapful number since it is divisible by the number (20) 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 29681640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49887090).

29681640 is an abundant number, since it is smaller than the sum of its proper divisors (70092540).

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

29681640 is a wasteful number, since it uses less digits than its factorization.

29681640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9184 (or 9171 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 29681640 is about 5448.0859024065. The cubic root of 29681640 is about 309.6202078030.

The spelling of 29681640 in words is "twenty-nine million, six hundred eighty-one thousand, six hundred forty".