551393721 has 24 divisors (see below), whose sum is σ = 823547400. Its totient is φ = 355228416.

The previous prime is 551393681. The next prime is 551393749. The reversal of 551393721 is 127393155.

551393721 is a `hidden beast` number, since 551 + 39 + 3 + 72 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1022121 + 550371600 = 1011^2 + 23460^2 .

It is not a de Polignac number, because 551393721 - 2⁷ = 551393593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (551393761) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 44061 + ... + 55173.

It is an arithmetic number, because the mean of its divisors is an integer number (34314475).

Almost surely, 2^551393721 is an apocalyptic number.

It is an amenable number.

551393721 is a deficient number, since it is larger than the sum of its proper divisors (272153679).

551393721 is a wasteful number, since it uses less digits than its factorization.

551393721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11305 (or 11302 counting only the distinct ones).

The product of its digits is 28350, while the sum is 36.

The square root of 551393721 is about 23481.7742302408. The cubic root of 551393721 is about 820.0127506445.

The spelling of 551393721 in words is "five hundred fifty-one million, three hundred ninety-three thousand, seven hundred twenty-one".