51400391 has 4 divisors (see below), whose sum is σ = 58743312. Its totient is φ = 44057472.

The previous prime is 51400361. The next prime is 51400411. The reversal of 51400391 is 19300415.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19300415 = 5 ⋅3860083.

It is a cyclic number.

It is not a de Polignac number, because 51400391 - 2¹⁴ = 51384007 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 (51400361) 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, 3671450 + ... + 3671463.

It is an arithmetic number, because the mean of its divisors is an integer number (14685828).

Almost surely, 2^51400391 is an apocalyptic number.

51400391 is a deficient number, since it is larger than the sum of its proper divisors (7342921).

51400391 is an equidigital number, since it uses as much as digits as its factorization.

51400391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7342920.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 51400391 is about 7169.4066002703. The cubic root of 51400391 is about 371.8109201170.

The spelling of 51400391 in words is "fifty-one million, four hundred thousand, three hundred ninety-one".