61881557 has 2 divisors, whose sum is σ = 61881558. Its totient is φ = 61881556.

The previous prime is 61881529. The next prime is 61881571. The reversal of 61881557 is 75518816.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52432081 + 9449476 = 7241^2 + 3074^2 .

It is a cyclic number.

It is not a de Polignac number, because 61881557 - 2⁶ = 61881493 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61881577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30940778 + 30940779.

It is an arithmetic number, because the mean of its divisors is an integer number (30940779).

Almost surely, 2^61881557 is an apocalyptic number.

It is an amenable number.

61881557 is a deficient number, since it is larger than the sum of its proper divisors (1).

61881557 is an equidigital number, since it uses as much as digits as its factorization.

61881557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67200, while the sum is 41.

The square root of 61881557 is about 7866.4831405146. The cubic root of 61881557 is about 395.5369655967.

The spelling of 61881557 in words is "sixty-one million, eight hundred eighty-one thousand, five hundred fifty-seven".