51440191 has 16 divisors (see below), whose sum is σ = 58254336. Its totient is φ = 45000000.

The previous prime is 51440189. The next prime is 51440197. The reversal of 51440191 is 19104415.

It is a 7-Lehmer number, since φ(51440191) divides (51440191-1)⁷.

It is a cyclic number.

It is not a de Polignac number, because 51440191 - 2¹ = 51440189 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 (51440197) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85291 + ... + 85891.

It is an arithmetic number, because the mean of its divisors is an integer number (3640896).

Almost surely, 2^51440191 is an apocalyptic number.

51440191 is a deficient number, since it is larger than the sum of its proper divisors (6814145).

51440191 is a wasteful number, since it uses less digits than its factorization.

51440191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 51440191 is about 7172.1817461634. The cubic root of 51440191 is about 371.9068613899.

The spelling of 51440191 in words is "fifty-one million, four hundred forty thousand, one hundred ninety-one".