61697781 has 20 divisors (see below), whose sum is σ = 95142784. Its totient is φ = 39803400.

The previous prime is 61697773. The next prime is 61697803. The reversal of 61697781 is 18779616.

It is not a de Polignac number, because 61697781 - 2³ = 61697773 is a prime.

It is a super-2 number, since 2×61697781² = 7613232360647922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61697081) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9775 + ... + 14796.

Almost surely, 2^61697781 is an apocalyptic number.

It is an amenable number.

61697781 is a deficient number, since it is larger than the sum of its proper divisors (33445003).

61697781 is a wasteful number, since it uses less digits than its factorization.

61697781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24614 (or 24605 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 61697781 is about 7854.7935046060. The cubic root of 61697781 is about 395.1450217910.

The spelling of 61697781 in words is "sixty-one million, six hundred ninety-seven thousand, seven hundred eighty-one".