551220021 has 48 divisors (see below), whose sum is σ = 901135872. Its totient is φ = 321667200.

The previous prime is 551220017. The next prime is 551220029. The reversal of 551220021 is 120022155.

It is not a de Polignac number, because 551220021 - 2² = 551220017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 551219976 and 551220003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (551220029) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 898911 + ... + 899523.

It is an arithmetic number, because the mean of its divisors is an integer number (18773664).

Almost surely, 2^551220021 is an apocalyptic number.

It is an amenable number.

551220021 is a deficient number, since it is larger than the sum of its proper divisors (349915851).

551220021 is a wasteful number, since it uses less digits than its factorization.

551220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 954 (or 951 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 551220021 is about 23478.0753257161. The cubic root of 551220021 is about 819.9266348203.

Adding to 551220021 its reverse (120022155), we get a palindrome (671242176).

The spelling of 551220021 in words is "five hundred fifty-one million, two hundred twenty thousand, twenty-one".