20720987 has 8 divisors (see below), whose sum is σ = 23710176. Its totient is φ = 17739072.

The previous prime is 20720971. The next prime is 20721013. The reversal of 20720987 is 78902702.

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 20720987 - 2⁴ = 20720971 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20720087) 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, 7463 + ... + 9855.

It is an arithmetic number, because the mean of its divisors is an integer number (2963772).

Almost surely, 2^20720987 is an apocalyptic number.

20720987 is a deficient number, since it is larger than the sum of its proper divisors (2989189).

20720987 is a wasteful number, since it uses less digits than its factorization.

20720987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3637.

The product of its (nonzero) digits is 14112, while the sum is 35.

The square root of 20720987 is about 4552.0310851311. The cubic root of 20720987 is about 274.6650997557.

The spelling of 20720987 in words is "twenty million, seven hundred twenty thousand, nine hundred eighty-seven".