551687621 has 4 divisors (see below), whose sum is σ = 584139852. Its totient is φ = 519235392.

The previous prime is 551687603. The next prime is 551687639. The reversal of 551687621 is 126786155.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 126786155 = 5 ⋅25357231.

It is an interprime number because it is at equal distance from previous prime (551687603) and next prime (551687639).

It can be written as a sum of positive squares in 2 ways, for example, as 339664900 + 212022721 = 18430^2 + 14561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-551687621 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 (551687671) 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, 16226090 + ... + 16226123.

It is an arithmetic number, because the mean of its divisors is an integer number (146034963).

Almost surely, 2^551687621 is an apocalyptic number.

It is an amenable number.

551687621 is a deficient number, since it is larger than the sum of its proper divisors (32452231).

551687621 is a wasteful number, since it uses less digits than its factorization.

551687621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32452230.

The product of its digits is 100800, while the sum is 41.

The square root of 551687621 is about 23488.0314415661. The cubic root of 551687621 is about 820.1584172416.

The spelling of 551687621 in words is "five hundred fifty-one million, six hundred eighty-seven thousand, six hundred twenty-one".