61855813 has 2 divisors, whose sum is σ = 61855814. Its totient is φ = 61855812.

The previous prime is 61855799. The next prime is 61855817. The reversal of 61855813 is 31855816.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59490369 + 2365444 = 7713^2 + 1538^2 .

It is a cyclic number.

It is not a de Polignac number, because 61855813 - 2²¹ = 59758661 is a prime.

It is a super-2 number, since 2×61855813² = 7652283203781938, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61855817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30927906 + 30927907.

It is an arithmetic number, because the mean of its divisors is an integer number (30927907).

Almost surely, 2^61855813 is an apocalyptic number.

It is an amenable number.

61855813 is a deficient number, since it is larger than the sum of its proper divisors (1).

61855813 is an equidigital number, since it uses as much as digits as its factorization.

61855813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 28800, while the sum is 37.

The square root of 61855813 is about 7864.8466609337. The cubic root of 61855813 is about 395.4821074854.

The spelling of 61855813 in words is "sixty-one million, eight hundred fifty-five thousand, eight hundred thirteen".