55621561 has 2 divisors, whose sum is σ = 55621562. Its totient is φ = 55621560.

The previous prime is 55621549. The next prime is 55621627. The reversal of 55621561 is 16512655.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52128400 + 3493161 = 7220^2 + 1869^2 .

It is a cyclic number.

It is not a de Polignac number, because 55621561 - 2¹¹ = 55619513 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (55621541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27810780 + 27810781.

It is an arithmetic number, because the mean of its divisors is an integer number (27810781).

Almost surely, 2^55621561 is an apocalyptic number.

It is an amenable number.

55621561 is a deficient number, since it is larger than the sum of its proper divisors (1).

55621561 is an equidigital number, since it uses as much as digits as its factorization.

55621561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9000, while the sum is 31.

The square root of 55621561 is about 7457.9863904408. The cubic root of 55621561 is about 381.7224691222.

The spelling of 55621561 in words is "fifty-five million, six hundred twenty-one thousand, five hundred sixty-one".