21191900542 has 4 divisors (see below), whose sum is σ = 31787850816. Its totient is φ = 10595950270.

The previous prime is 21191900537. The next prime is 21191900551. The reversal of 21191900542 is 24500919112.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21191900498 and 21191900507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5297975134 + ... + 5297975137.

It is an arithmetic number, because the mean of its divisors is an integer number (7946962704).

Almost surely, 2^21191900542 is an apocalyptic number.

21191900542 is a deficient number, since it is larger than the sum of its proper divisors (10595950274).

21191900542 is a wasteful number, since it uses less digits than its factorization.

21191900542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10595950273.

The product of its (nonzero) digits is 6480, while the sum is 34.

The spelling of 21191900542 in words is "twenty-one billion, one hundred ninety-one million, nine hundred thousand, five hundred forty-two".