61836721 has 2 divisors, whose sum is σ = 61836722. Its totient is φ = 61836720.

The previous prime is 61836713. The next prime is 61836727. The reversal of 61836721 is 12763816.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61779600 + 57121 = 7860^2 + 239^2 .

It is a cyclic number.

It is not a de Polignac number, because 61836721 - 2³ = 61836713 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (61836727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30918360 + 30918361.

It is an arithmetic number, because the mean of its divisors is an integer number (30918361).

Almost surely, 2^61836721 is an apocalyptic number.

It is an amenable number.

61836721 is a deficient number, since it is larger than the sum of its proper divisors (1).

61836721 is an equidigital number, since it uses as much as digits as its factorization.

61836721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 34.

The square root of 61836721 is about 7863.6328118752. The cubic root of 61836721 is about 395.4414143476.

The spelling of 61836721 in words is "sixty-one million, eight hundred thirty-six thousand, seven hundred twenty-one".