1620665721615 has 8 divisors (see below), whose sum is σ = 2593065154608. Its totient is φ = 864355051520.

The previous prime is 1620665721611. The next prime is 1620665721641. The reversal of 1620665721615 is 5161275660261.

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

It is not a de Polignac number, because 1620665721615 - 2² = 1620665721611 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620665721611) 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, 54022190706 + ... + 54022190735.

It is an arithmetic number, because the mean of its divisors is an integer number (324133144326).

Almost surely, 2^{1620665721615} is an apocalyptic number.

1620665721615 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1620665721615 is a deficient number, since it is larger than the sum of its proper divisors (972399432993).

1620665721615 is a wasteful number, since it uses less digits than its factorization.

1620665721615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108044381449.

The product of its (nonzero) digits is 907200, while the sum is 48.

The spelling of 1620665721615 in words is "one trillion, six hundred twenty billion, six hundred sixty-five million, seven hundred twenty-one thousand, six hundred fifteen".