51821554 has 4 divisors (see below), whose sum is σ = 77732334. Its totient is φ = 25910776.

The previous prime is 51821537. The next prime is 51821557. The reversal of 51821554 is 45512815.

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

It can be written as a sum of positive squares in only one way, i.e., 42549529 + 9272025 = 6523^2 + 3045^2 .

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (51821557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12955387 + ... + 12955390.

Almost surely, 2^51821554 is an apocalyptic number.

51821554 is a deficient number, since it is larger than the sum of its proper divisors (25910780).

51821554 is a wasteful number, since it uses less digits than its factorization.

51821554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25910779.

The product of its digits is 8000, while the sum is 31.

The square root of 51821554 is about 7198.7189138068. The cubic root of 51821554 is about 372.8236701509.

The spelling of 51821554 in words is "fifty-one million, eight hundred twenty-one thousand, five hundred fifty-four".