53509991 has 4 divisors (see below), whose sum is σ = 54417000. Its totient is φ = 52602984.

The previous prime is 53509969. The next prime is 53510003. The reversal of 53509991 is 19990535.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19990535 = 5 ⋅3998107.

It is not a de Polignac number, because 53509991 - 2⁶ = 53509927 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 (53509921) 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, 453416 + ... + 453533.

It is an arithmetic number, because the mean of its divisors is an integer number (13604250).

Almost surely, 2^53509991 is an apocalyptic number.

53509991 is a deficient number, since it is larger than the sum of its proper divisors (907009).

53509991 is an equidigital number, since it uses as much as digits as its factorization.

53509991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907008.

The product of its (nonzero) digits is 54675, while the sum is 41.

The square root of 53509991 is about 7315.0523579808. The cubic root of 53509991 is about 376.8295565961.

The spelling of 53509991 in words is "fifty-three million, five hundred nine thousand, nine hundred ninety-one".