51801661 has 4 divisors (see below), whose sum is σ = 52903872. Its totient is φ = 50699452.

The previous prime is 51801647. The next prime is 51801677. The reversal of 51801661 is 16610815.

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 51801661 - 2¹¹ = 51799613 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 (51801611) 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, 551035 + ... + 551128.

It is an arithmetic number, because the mean of its divisors is an integer number (13225968).

Almost surely, 2^51801661 is an apocalyptic number.

It is an amenable number.

51801661 is a deficient number, since it is larger than the sum of its proper divisors (1102211).

51801661 is a wasteful number, since it uses less digits than its factorization.

51801661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1102210.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 51801661 is about 7197.3370770029. The cubic root of 51801661 is about 372.7759581475.

The spelling of 51801661 in words is "fifty-one million, eight hundred one thousand, six hundred sixty-one".