51220661 has 4 divisors (see below), whose sum is σ = 51489024. Its totient is φ = 50952300.

The previous prime is 51220639. The next prime is 51220703. The reversal of 51220661 is 16602215.

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 51220661 - 2¹⁸ = 50958517 is a prime.

It is a super-2 number, since 2×51220661² = 5247112226553842, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51220621) 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, 133895 + ... + 134276.

It is an arithmetic number, because the mean of its divisors is an integer number (12872256).

Almost surely, 2^51220661 is an apocalyptic number.

It is an amenable number.

51220661 is a deficient number, since it is larger than the sum of its proper divisors (268363).

51220661 is a wasteful number, since it uses less digits than its factorization.

51220661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268362.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 51220661 is about 7156.8611136447. The cubic root of 51220661 is about 371.3770478193.

Adding to 51220661 its reverse (16602215), we get a palindrome (67822876).

The spelling of 51220661 in words is "fifty-one million, two hundred twenty thousand, six hundred sixty-one".