51720091 has 4 divisors (see below), whose sum is σ = 51757000. Its totient is φ = 51683184.

The previous prime is 51720089. The next prime is 51720101. The reversal of 51720091 is 19002715.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51720091 - 2¹ = 51720089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51721091) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16266 + ... + 19183.

It is an arithmetic number, because the mean of its divisors is an integer number (12939250).

Almost surely, 2^51720091 is an apocalyptic number.

51720091 is a deficient number, since it is larger than the sum of its proper divisors (36909).

51720091 is a wasteful number, since it uses less digits than its factorization.

51720091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36908.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 51720091 is about 7191.6681653146. The cubic root of 51720091 is about 372.5801902339.

The spelling of 51720091 in words is "fifty-one million, seven hundred twenty thousand, ninety-one".