1821397919 has 8 divisors (see below), whose sum is σ = 1988064000. Its totient is φ = 1654912600.

The previous prime is 1821397891. The next prime is 1821397937. The reversal of 1821397919 is 9197931281.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1821397919 - 2¹² = 1821393823 is a prime.

It is a super-2 number, since 2×1821397919² = 6634980758675061122, 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 (1821397819) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23669 + ... + 64830.

It is an arithmetic number, because the mean of its divisors is an integer number (248508000).

Almost surely, 2^1821397919 is an apocalyptic number.

1821397919 is a deficient number, since it is larger than the sum of its proper divisors (166666081).

1821397919 is a wasteful number, since it uses less digits than its factorization.

1821397919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90381.

The product of its digits is 244944, while the sum is 50.

The square root of 1821397919 is about 42677.8387339378. The cubic root of 1821397919 is about 1221.2416631648.

The spelling of 1821397919 in words is "one billion, eight hundred twenty-one million, three hundred ninety-seven thousand, nine hundred nineteen".