51423440 has 40 divisors (see below), whose sum is σ = 119911968. Its totient is φ = 20508800.

The previous prime is 51423439. The next prime is 51423457. The reversal of 51423440 is 4432415.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34715 + ... + 36165.

Almost surely, 2^51423440 is an apocalyptic number.

It is an amenable number.

51423440 is an abundant number, since it is smaller than the sum of its proper divisors (68488528).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51423440 is a wasteful number, since it uses less digits than its factorization.

51423440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1907 (or 1901 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 23.

The square root of 51423440 is about 7171.0138753178. The cubic root of 51423440 is about 371.8664877180.

Adding to 51423440 its reverse (4432415), we get a palindrome (55855855).

Subtracting from 51423440 its reverse (4432415), we obtain a square (46991025 = 6855²).

The spelling of 51423440 in words is "fifty-one million, four hundred twenty-three thousand, four hundred forty".