51988991 has 2 divisors, whose sum is σ = 51988992. Its totient is φ = 51988990.

The previous prime is 51988957. The next prime is 51988999. The reversal of 51988991 is 19988915.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 51988991 - 2¹⁴ = 51972607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51988999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25994495 + 25994496.

It is an arithmetic number, because the mean of its divisors is an integer number (25994496).

Almost surely, 2^51988991 is an apocalyptic number.

51988991 is a deficient number, since it is larger than the sum of its proper divisors (1).

51988991 is an equidigital number, since it uses as much as digits as its factorization.

51988991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 50.

The square root of 51988991 is about 7210.3391737144. The cubic root of 51988991 is about 373.2247733000.

The spelling of 51988991 in words is "fifty-one million, nine hundred eighty-eight thousand, nine hundred ninety-one".