51921890 has 16 divisors (see below), whose sum is σ = 96682680. Its totient is φ = 20052480.

The previous prime is 51921853. The next prime is 51921899. The reversal of 51921890 is 9812915.

It can be written as a sum of positive squares in 4 ways, for example, as 38180041 + 13741849 = 6179^2 + 3707^2 .

It is a super-2 number, since 2×51921890² = 5391765322344200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 51921890.

It is not an unprimeable number, because it can be changed into a prime (51921899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89231 + ... + 89810.

Almost surely, 2^51921890 is an apocalyptic number.

51921890 is a deficient number, since it is larger than the sum of its proper divisors (44760790).

51921890 is a wasteful number, since it uses less digits than its factorization.

51921890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179077.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 51921890 is about 7205.6845615111. The cubic root of 51921890 is about 373.0641332797.

The spelling of 51921890 in words is "fifty-one million, nine hundred twenty-one thousand, eight hundred ninety".