20479991 has 6 divisors (see below), whose sum is σ = 23823720. Its totient is φ = 17554236.

The previous prime is 20479937. The next prime is 20479999. The reversal of 20479991 is 19997402.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-20479991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20479999) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 208931 + ... + 209028.

It is an arithmetic number, because the mean of its divisors is an integer number (3970620).

Almost surely, 2^20479991 is an apocalyptic number.

20479991 is a deficient number, since it is larger than the sum of its proper divisors (3343729).

20479991 is an equidigital number, since it uses as much as digits as its factorization.

20479991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417973 (or 417966 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 20479991 is about 4525.4824052249. The cubic root of 20479991 is about 273.5961113907.

The spelling of 20479991 in words is "twenty million, four hundred seventy-nine thousand, nine hundred ninety-one".