1918009621 has 8 divisors (see below), whose sum is σ = 2098699488. Its totient is φ = 1738374000.

The previous prime is 1918009619. The next prime is 1918009661. The reversal of 1918009621 is 1269008191.

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

It is not a de Polignac number, because 1918009621 - 2¹ = 1918009619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918009601) 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, 259750 + ... + 267031.

It is an arithmetic number, because the mean of its divisors is an integer number (262337436).

Almost surely, 2^1918009621 is an apocalyptic number.

1918009621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1918009621 is a deficient number, since it is larger than the sum of its proper divisors (180689867).

1918009621 is a wasteful number, since it uses less digits than its factorization.

1918009621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527123.

The product of its (nonzero) digits is 7776, while the sum is 37.

The square root of 1918009621 is about 43795.0867221427. The cubic root of 1918009621 is about 1242.4633698364.

The spelling of 1918009621 in words is "one billion, nine hundred eighteen million, nine thousand, six hundred twenty-one".