6611721651 has 24 divisors (see below), whose sum is σ = 10233896400. Its totient is φ = 4098541056.

The previous prime is 6611721647. The next prime is 6611721731. The reversal of 6611721651 is 1561271166.

It is a happy number.

It is not a de Polignac number, because 6611721651 - 2² = 6611721647 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6611721601) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 247626 + ... + 273023.

It is an arithmetic number, because the mean of its divisors is an integer number (426412350).

Almost surely, 2^6611721651 is an apocalyptic number.

6611721651 is a deficient number, since it is larger than the sum of its proper divisors (3622174749).

6611721651 is a wasteful number, since it uses less digits than its factorization.

6611721651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520755 (or 520752 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 6611721651 is about 81312.4938186008. The cubic root of 6611721651 is about 1876.8872637017.

The spelling of 6611721651 in words is "six billion, six hundred eleven million, seven hundred twenty-one thousand, six hundred fifty-one".