19121921 has 8 divisors (see below), whose sum is σ = 23534784. Its totient is φ = 15129360.

The previous prime is 19121909. The next prime is 19121953. The reversal of 19121921 is 12912191.

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

It is a cyclic number.

It is not a de Polignac number, because 19121921 - 2⁶ = 19121857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19121981) 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, 104975 + ... + 105156.

It is an arithmetic number, because the mean of its divisors is an integer number (2941848).

Almost surely, 2^19121921 is an apocalyptic number.

It is an amenable number.

19121921 is a deficient number, since it is larger than the sum of its proper divisors (4412863).

19121921 is a wasteful number, since it uses less digits than its factorization.

19121921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210151.

The product of its digits is 324, while the sum is 26.

The square root of 19121921 is about 4372.8618775351. The cubic root of 19121921 is about 267.4097101164.

The spelling of 19121921 in words is "nineteen million, one hundred twenty-one thousand, nine hundred twenty-one".