51251661 has 12 divisors (see below), whose sum is σ = 74212320. Its totient is φ = 34083720.

The previous prime is 51251647. The next prime is 51251687. The reversal of 51251661 is 16615215.

It is a happy number.

It is not a de Polignac number, because 51251661 - 2⁶ = 51251597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51251611) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3025 + ... + 10566.

It is an arithmetic number, because the mean of its divisors is an integer number (6184360).

Almost surely, 2^51251661 is an apocalyptic number.

It is an amenable number.

51251661 is a deficient number, since it is larger than the sum of its proper divisors (22960659).

51251661 is a wasteful number, since it uses less digits than its factorization.

51251661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14016 (or 14013 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 51251661 is about 7159.0265399704. The cubic root of 51251661 is about 371.4519548747.

Adding to 51251661 its reverse (16615215), we get a palindrome (67866876).

It can be divided in two parts, 5125 and 1661, that added together give a triangular number (6786 = T₁₁₆).

The spelling of 51251661 in words is "fifty-one million, two hundred fifty-one thousand, six hundred sixty-one".