61555381 has 2 divisors, whose sum is σ = 61555382. Its totient is φ = 61555380.

The previous prime is 61555343. The next prime is 61555393. The reversal of 61555381 is 18355516.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51251281 + 10304100 = 7159^2 + 3210^2 .

It is a cyclic number.

It is not a de Polignac number, because 61555381 - 2⁷ = 61555253 is a prime.

It is a super-2 number, since 2×61555381² = 7578129860110322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61555331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30777690 + 30777691.

It is an arithmetic number, because the mean of its divisors is an integer number (30777691).

Almost surely, 2^61555381 is an apocalyptic number.

It is an amenable number.

61555381 is a deficient number, since it is larger than the sum of its proper divisors (1).

61555381 is an equidigital number, since it uses as much as digits as its factorization.

61555381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18000, while the sum is 34.

The square root of 61555381 is about 7845.7237397196. The cubic root of 61555381 is about 394.8407861249.

The spelling of 61555381 in words is "sixty-one million, five hundred fifty-five thousand, three hundred eighty-one".