1921550401 has 4 divisors (see below), whose sum is σ = 1922169600. Its totient is φ = 1920931204.

The previous prime is 1921550369. The next prime is 1921550437. The reversal of 1921550401 is 1040551291.

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 1921550401 - 2⁵ = 1921550369 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1921550401.

It is not an unprimeable number, because it can be changed into a prime (1921550441) 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, 304921 + ... + 311158.

It is an arithmetic number, because the mean of its divisors is an integer number (480542400).

Almost surely, 2^1921550401 is an apocalyptic number.

It is an amenable number.

1921550401 is a deficient number, since it is larger than the sum of its proper divisors (619199).

1921550401 is an equidigital number, since it uses as much as digits as its factorization.

1921550401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 619198.

The product of its (nonzero) digits is 1800, while the sum is 28.

The square root of 1921550401 is about 43835.4924804091. The cubic root of 1921550401 is about 1243.2274579556.

The spelling of 1921550401 in words is "one billion, nine hundred twenty-one million, five hundred fifty thousand, four hundred one".