61781491 has 2 divisors, whose sum is σ = 61781492. Its totient is φ = 61781490.

The previous prime is 61781477. The next prime is 61781501. The reversal of 61781491 is 19418716.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 61781491 - 2²³ = 53392883 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61781491.

It is not a weakly prime, because it can be changed into another prime (61781591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30890745 + 30890746.

It is an arithmetic number, because the mean of its divisors is an integer number (30890746).

Almost surely, 2^61781491 is an apocalyptic number.

61781491 is a deficient number, since it is larger than the sum of its proper divisors (1).

61781491 is an equidigital number, since it uses as much as digits as its factorization.

61781491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 37.

The square root of 61781491 is about 7860.1202917004. The cubic root of 61781491 is about 395.3236486443.

The spelling of 61781491 in words is "sixty-one million, seven hundred eighty-one thousand, four hundred ninety-one".