21091954042 has 8 divisors (see below), whose sum is σ = 31827380256. Its totient is φ = 10482827292.

The previous prime is 21091953997. The next prime is 21091954049. The reversal of 21091954042 is 24045919012.

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

It is a junction number, because it is equal to n+sod(n) for n = 21091953992 and 21091954010.

It is not an unprimeable number, because it can be changed into a prime (21091954049) 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, 31574448 + ... + 31575115.

It is an arithmetic number, because the mean of its divisors is an integer number (3978422532).

Almost surely, 2^21091954042 is an apocalyptic number.

21091954042 is a deficient number, since it is larger than the sum of its proper divisors (10735426214).

21091954042 is a wasteful number, since it uses less digits than its factorization.

21091954042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63149732.

The product of its (nonzero) digits is 25920, while the sum is 37.

The spelling of 21091954042 in words is "twenty-one billion, ninety-one million, nine hundred fifty-four thousand, forty-two".