1620777601 has 4 divisors (see below), whose sum is σ = 1660308804. Its totient is φ = 1581246400.

The previous prime is 1620777581. The next prime is 1620777617. The reversal of 1620777601 is 1067770261.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1067770261 = 8147 ⋅131063.

It can be written as a sum of positive squares in 2 ways, for example, as 283046976 + 1337730625 = 16824^2 + 36575^2 .

It is a cyclic number.

It is not a de Polignac number, because 1620777601 - 2⁹ = 1620777089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1620777001) 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, 19765540 + ... + 19765621.

It is an arithmetic number, because the mean of its divisors is an integer number (415077201).

Almost surely, 2^1620777601 is an apocalyptic number.

It is an amenable number.

1620777601 is a deficient number, since it is larger than the sum of its proper divisors (39531203).

1620777601 is an equidigital number, since it uses as much as digits as its factorization.

1620777601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39531202.

The product of its (nonzero) digits is 24696, while the sum is 37.

The square root of 1620777601 is about 40258.8822621791. The cubic root of 1620777601 is about 1174.6481761808.

The spelling of 1620777601 in words is "one billion, six hundred twenty million, seven hundred seventy-seven thousand, six hundred one".