1620787081 has 9 divisors (see below), whose sum is σ = 1638819399. Its totient is φ = 1602952344.

The previous prime is 1620787079. The next prime is 1620787093. The reversal of 1620787081 is 1807870261.

The square root of 1620787081 is 40259.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 90725625 + 1530061456 = 9525^2 + 39116^2 .

It is not a de Polignac number, because 1620787081 - 2¹ = 1620787079 is a prime.

It is a super-2 number, since 2×1620787081² = 5253901523873001122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1620787481) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5112735 + ... + 5113051.

Almost surely, 2^1620787081 is an apocalyptic number.

1620787081 is the 40259-th square number.

1620787081 is the 20130-th centered octagonal number.

It is an amenable number.

1620787081 is a deficient number, since it is larger than the sum of its proper divisors (18032318).

1620787081 is an frugal number, since it uses more digits than its factorization.

1620787081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888 (or 444 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 40.

The cubic root of 1620787081 is about 1174.6504663661.

The spelling of 1620787081 in words is "one billion, six hundred twenty million, seven hundred eighty-seven thousand, eighty-one".