61718991 has 8 divisors (see below), whose sum is σ = 83061504. Its totient is φ = 40761240.

The previous prime is 61718963. The next prime is 61719001. The reversal of 61718991 is 19981716.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 61718991 - 2⁶ = 61718927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61717991) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95815 + ... + 96456.

It is an arithmetic number, because the mean of its divisors is an integer number (10382688).

Almost surely, 2^61718991 is an apocalyptic number.

61718991 is a deficient number, since it is larger than the sum of its proper divisors (21342513).

61718991 is a wasteful number, since it uses less digits than its factorization.

61718991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192381.

The product of its digits is 27216, while the sum is 42.

The square root of 61718991 is about 7856.1435195648. The cubic root of 61718991 is about 395.1902965998.

The spelling of 61718991 in words is "sixty-one million, seven hundred eighteen thousand, nine hundred ninety-one".