51378557 has 4 divisors (see below), whose sum is σ = 52249440. Its totient is φ = 50507676.

The previous prime is 51378553. The next prime is 51378559. The reversal of 51378557 is 75587315.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51378557 - 2² = 51378553 is a prime.

It is a super-2 number, since 2×51378557² = 5279512238804498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51378553) 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, 435353 + ... + 435470.

It is an arithmetic number, because the mean of its divisors is an integer number (13062360).

Almost surely, 2^51378557 is an apocalyptic number.

It is an amenable number.

51378557 is a deficient number, since it is larger than the sum of its proper divisors (870883).

51378557 is an equidigital number, since it uses as much as digits as its factorization.

51378557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870882.

The product of its digits is 147000, while the sum is 41.

The square root of 51378557 is about 7167.8837183649. The cubic root of 51378557 is about 371.7582663711.

The spelling of 51378557 in words is "fifty-one million, three hundred seventy-eight thousand, five hundred fifty-seven".