1603665421 has 4 divisors (see below), whose sum is σ = 1604489344. Its totient is φ = 1602841500.

The previous prime is 1603665347. The next prime is 1603665499. The reversal of 1603665421 is 1245663061.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1603665421 - 2⁷ = 1603665293 is a prime.

It is a super-2 number, since 2×1603665421² = 5143485565022214482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1603665221) 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, 409035 + ... + 412936.

It is an arithmetic number, because the mean of its divisors is an integer number (401122336).

Almost surely, 2^1603665421 is an apocalyptic number.

It is an amenable number.

1603665421 is a deficient number, since it is larger than the sum of its proper divisors (823923).

1603665421 is an equidigital number, since it uses as much as digits as its factorization.

1603665421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 823922.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 1603665421 is about 40045.7915516724. The cubic root of 1603665421 is about 1170.4995604542.

The spelling of 1603665421 in words is "one billion, six hundred three million, six hundred sixty-five thousand, four hundred twenty-one".