61797991 has 4 divisors (see below), whose sum is σ = 62056800. Its totient is φ = 61539184.

The previous prime is 61797979. The next prime is 61798001. The reversal of 61797991 is 19979716.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 61797991 - 2⁵ = 61797959 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61797971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 129046 + ... + 129523.

It is an arithmetic number, because the mean of its divisors is an integer number (15514200).

Almost surely, 2^61797991 is an apocalyptic number.

61797991 is a deficient number, since it is larger than the sum of its proper divisors (258809).

61797991 is a wasteful number, since it uses less digits than its factorization.

61797991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258808.

The product of its digits is 214326, while the sum is 49.

The square root of 61797991 is about 7861.1698238875. The cubic root of 61797991 is about 395.3588385774.

The spelling of 61797991 in words is "sixty-one million, seven hundred ninety-seven thousand, nine hundred ninety-one".