51221557 has 4 divisors (see below), whose sum is σ = 52412800. Its totient is φ = 50030316.

The previous prime is 51221543. The next prime is 51221563. The reversal of 51221557 is 75512215.

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 51221557 - 2¹⁵ = 51188789 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 (51221507) 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, 595557 + ... + 595642.

It is an arithmetic number, because the mean of its divisors is an integer number (13103200).

Almost surely, 2^51221557 is an apocalyptic number.

It is an amenable number.

51221557 is a deficient number, since it is larger than the sum of its proper divisors (1191243).

51221557 is a wasteful number, since it uses less digits than its factorization.

51221557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1191242.

The product of its digits is 3500, while the sum is 28.

The square root of 51221557 is about 7156.9237106455. The cubic root of 51221557 is about 371.3792132989.

The spelling of 51221557 in words is "fifty-one million, two hundred twenty-one thousand, five hundred fifty-seven".