51240661 has 4 divisors (see below), whose sum is σ = 51460812. Its totient is φ = 51020512.

The previous prime is 51240647. The next prime is 51240677. The reversal of 51240661 is 16604215.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28143025 + 23097636 = 5305^2 + 4806^2 .

It is a cyclic number.

It is not a de Polignac number, because 51240661 - 2¹⁷ = 51109589 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 (51240961) 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, 109726 + ... + 110191.

It is an arithmetic number, because the mean of its divisors is an integer number (12865203).

Almost surely, 2^51240661 is an apocalyptic number.

It is an amenable number.

51240661 is a deficient number, since it is larger than the sum of its proper divisors (220151).

51240661 is a wasteful number, since it uses less digits than its factorization.

51240661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220150.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 51240661 is about 7158.2582378676. The cubic root of 51240661 is about 371.4253784101.

Adding to 51240661 its reverse (16604215), we get a palindrome (67844876).

The spelling of 51240661 in words is "fifty-one million, two hundred forty thousand, six hundred sixty-one".