61645891 has 2 divisors, whose sum is σ = 61645892. Its totient is φ = 61645890.

The previous prime is 61645867. The next prime is 61645979. The reversal of 61645891 is 19854616.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61645891 - 2⁹ = 61645379 is a prime.

It is not a weakly prime, because it can be changed into another prime (61645091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30822945 + 30822946.

It is an arithmetic number, because the mean of its divisors is an integer number (30822946).

Almost surely, 2^61645891 is an apocalyptic number.

61645891 is a deficient number, since it is larger than the sum of its proper divisors (1).

61645891 is an equidigital number, since it uses as much as digits as its factorization.

61645891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 40.

The square root of 61645891 is about 7851.4897312548. The cubic root of 61645891 is about 395.0342137752.

The spelling of 61645891 in words is "sixty-one million, six hundred forty-five thousand, eight hundred ninety-one".