51537781 has 8 divisors (see below), whose sum is σ = 53658584. Its totient is φ = 49455360.

The previous prime is 51537769. The next prime is 51537797. The reversal of 51537781 is 18773515.

It can be written as a sum of positive squares in 4 ways, for example, as 10692900 + 40844881 = 3270^2 + 6391^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51537781 - 2¹³ = 51529589 is a prime.

It is a super-2 number, since 2×51537781² = 5312285740807922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 51537781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51537701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6840 + ... + 12241.

It is an arithmetic number, because the mean of its divisors is an integer number (6707323).

Almost surely, 2^51537781 is an apocalyptic number.

It is an amenable number.

51537781 is a deficient number, since it is larger than the sum of its proper divisors (2120803).

51537781 is a wasteful number, since it uses less digits than its factorization.

51537781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19191.

The product of its digits is 29400, while the sum is 37.

The square root of 51537781 is about 7178.9818916055. The cubic root of 51537781 is about 372.1419011000.

The spelling of 51537781 in words is "fifty-one million, five hundred thirty-seven thousand, seven hundred eighty-one".