19901619421 has 4 divisors (see below), whose sum is σ = 19919862144. Its totient is φ = 19883376700.

The previous prime is 19901619371. The next prime is 19901619461. The reversal of 19901619421 is 12491610991.

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 a de Polignac number, because none of the positive numbers 2^k-19901619421 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 (19901619461) 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, 9119725 + ... + 9121906.

It is an arithmetic number, because the mean of its divisors is an integer number (4979965536).

Almost surely, 2^19901619421 is an apocalyptic number.

It is an amenable number.

19901619421 is a deficient number, since it is larger than the sum of its proper divisors (18242723).

19901619421 is a wasteful number, since it uses less digits than its factorization.

19901619421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18242722.

The product of its (nonzero) digits is 34992, while the sum is 43.

The spelling of 19901619421 in words is "nineteen billion, nine hundred one million, six hundred nineteen thousand, four hundred twenty-one".