29691981 has 32 divisors (see below), whose sum is σ = 48297600.
Its totient is φ = 17879040.
The previous prime is 29691967. The next prime is 29691989. The reversal of 29691981 is 18919692.
It is not a de Polignac number, because 29691981 - 213 = 29683789 is a prime.
It is a super-2 number, since 2×296919812 = 1763227471408722, which contains 22 as substring.
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 congruent number.
It is not an unprimeable number, because it can be changed into a prime (29691989) by changing a digit.
It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 76135 + ... + 76523.
It is an arithmetic number, because the mean of its divisors is an integer number (1509300).
Almost surely, 229691981 is an apocalyptic number.
It is an amenable number.
29691981 is a deficient number, since it is larger than the sum of its proper divisors (18605619).
29691981 is a wasteful number, since it uses less digits than its factorization.
29691981 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 666 (or 660 counting only the distinct ones).
The product of its digits is 69984, while the sum is 45.
The square root of 29691981 is about 5449.0348686717.
The cubic root of 29691981 is about 309.6561605650.
It can be divided in two parts, 2969 and 1981, that added together give a triangular number (4950 = T99).
The spelling of 29691981 in words is "twenty-nine million, six hundred ninety-one thousand, nine hundred eighty-one".