1806990421 has 4 divisors (see below), whose sum is σ = 1902095200. Its totient is φ = 1711885644.

The previous prime is 1806990347. The next prime is 1806990433. The reversal of 1806990421 is 1240996081.

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 1806990421 - 2¹¹ = 1806988373 is a prime.

It is a super-3 number, since 3×1806990421³ (a number of 29 digits) contains 333 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 (1806990461) 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, 47552361 + ... + 47552398.

It is an arithmetic number, because the mean of its divisors is an integer number (475523800).

Almost surely, 2^1806990421 is an apocalyptic number.

It is an amenable number.

1806990421 is a deficient number, since it is larger than the sum of its proper divisors (95104779).

1806990421 is an equidigital number, since it uses as much as digits as its factorization.

1806990421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95104778.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 1806990421 is about 42508.7099427870. The cubic root of 1806990421 is about 1218.0130743588.

The spelling of 1806990421 in words is "one billion, eight hundred six million, nine hundred ninety thousand, four hundred twenty-one".