1551055621 has 2 divisors, whose sum is σ = 1551055622. Its totient is φ = 1551055620.

The previous prime is 1551055609. The next prime is 1551055637. The reversal of 1551055621 is 1265501551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1287804996 + 263250625 = 35886^2 + 16225^2 .

It is a cyclic number.

It is not a de Polignac number, because 1551055621 - 2¹³ = 1551047429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1551055321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775527810 + 775527811.

It is an arithmetic number, because the mean of its divisors is an integer number (775527811).

Almost surely, 2^1551055621 is an apocalyptic number.

It is an amenable number.

1551055621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551055621 is an equidigital number, since it uses as much as digits as its factorization.

1551055621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7500, while the sum is 31.

The square root of 1551055621 is about 39383.4434883493. The cubic root of 1551055621 is about 1157.5571911714.

The spelling of 1551055621 in words is "one billion, five hundred fifty-one million, fifty-five thousand, six hundred twenty-one".