91720929 has 8 divisors (see below), whose sum is σ = 122730912. Its totient is φ = 60929120.

The previous prime is 91720921. The next prime is 91720949. The reversal of 91720929 is 92902719.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91720929 - 2³ = 91720921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91720921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53559 + ... + 55244.

It is an arithmetic number, because the mean of its divisors is an integer number (15341364).

Almost surely, 2^91720929 is an apocalyptic number.

It is an amenable number.

91720929 is a deficient number, since it is larger than the sum of its proper divisors (31009983).

91720929 is a wasteful number, since it uses less digits than its factorization.

91720929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109087.

The product of its (nonzero) digits is 20412, while the sum is 39.

The square root of 91720929 is about 9577.1044162628. The cubic root of 91720929 is about 450.9788224463.

The spelling of 91720929 in words is "ninety-one million, seven hundred twenty thousand, nine hundred twenty-nine".