6615620721611 has 4 divisors (see below), whose sum is σ = 7217040787224. Its totient is φ = 6014200656000.

The previous prime is 6615620721583. The next prime is 6615620721623. The reversal of 6615620721611 is 1161270265166.

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 6615620721611 - 2¹⁸ = 6615620459467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6615620721641) 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, 300710032790 + ... + 300710032811.

It is an arithmetic number, because the mean of its divisors is an integer number (1804260196806).

Almost surely, 2^{6615620721611} is an apocalyptic number.

6615620721611 is a deficient number, since it is larger than the sum of its proper divisors (601420065613).

6615620721611 is a wasteful number, since it uses less digits than its factorization.

6615620721611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601420065612.

The product of its (nonzero) digits is 181440, while the sum is 44.

Adding to 6615620721611 its reverse (1161270265166), we get a palindrome (7776890986777).

The spelling of 6615620721611 in words is "six trillion, six hundred fifteen billion, six hundred twenty million, seven hundred twenty-one thousand, six hundred eleven".