61623781 has 2 divisors, whose sum is σ = 61623782. Its totient is φ = 61623780.

The previous prime is 61623769. The next prime is 61623791. The reversal of 61623781 is 18732616.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59814756 + 1809025 = 7734^2 + 1345^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61623781 is a prime.

It is a super-2 number, since 2×61623781² = 7594980769471922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61623701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30811890 + 30811891.

It is an arithmetic number, because the mean of its divisors is an integer number (30811891).

Almost surely, 2^61623781 is an apocalyptic number.

It is an amenable number.

61623781 is a deficient number, since it is larger than the sum of its proper divisors (1).

61623781 is an equidigital number, since it uses as much as digits as its factorization.

61623781 is an odious number, because the sum of its binary digits is odd.

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

The square root of 61623781 is about 7850.0815919327. The cubic root of 61623781 is about 394.9869802898.

The spelling of 61623781 in words is "sixty-one million, six hundred twenty-three thousand, seven hundred eighty-one".