61721805 has 8 divisors (see below), whose sum is σ = 98754912. Its totient is φ = 32918288.

The previous prime is 61721789. The next prime is 61721819. The reversal of 61721805 is 50812716.

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

It is a cyclic number.

It is not a de Polignac number, because 61721805 - 2⁴ = 61721789 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2057379 + ... + 2057408.

It is an arithmetic number, because the mean of its divisors is an integer number (12344364).

Almost surely, 2^61721805 is an apocalyptic number.

It is an amenable number.

61721805 is a deficient number, since it is larger than the sum of its proper divisors (37033107).

61721805 is a wasteful number, since it uses less digits than its factorization.

61721805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4114795.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 61721805 is about 7856.3226130296. The cubic root of 61721805 is about 395.1963025772.

It can be divided in two parts, 61721 and 805, that added together give a palindrome (62526).

The spelling of 61721805 in words is "sixty-one million, seven hundred twenty-one thousand, eight hundred five".