1605620421 has 16 divisors (see below), whose sum is σ = 2379366400. Its totient is φ = 1070112384.

The previous prime is 1605620413. The next prime is 1605620453. The reversal of 1605620421 is 1240265061.

1605620421 is a `hidden beast` number, since 1 + 60 + 562 + 0 + 42 + 1 = 666.

It is not a de Polignac number, because 1605620421 - 2³ = 1605620413 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1605620491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 132405 + ... + 144021.

It is an arithmetic number, because the mean of its divisors is an integer number (148710400).

Almost surely, 2^1605620421 is an apocalyptic number.

It is an amenable number.

1605620421 is a deficient number, since it is larger than the sum of its proper divisors (773745979).

1605620421 is a wasteful number, since it uses less digits than its factorization.

1605620421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16745 (or 16739 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 1605620421 is about 40070.1936731032. The cubic root of 1605620421 is about 1170.9750123687.

Adding to 1605620421 its reverse (1240265061), we get a palindrome (2845885482).

The spelling of 1605620421 in words is "one billion, six hundred five million, six hundred twenty thousand, four hundred twenty-one".