21420723890 has 16 divisors (see below), whose sum is σ = 38559229632. Its totient is φ = 8567861424.

The previous prime is 21420723881. The next prime is 21420723941. The reversal of 21420723890 is 9832702412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 226277 + ... + 306663.

It is an arithmetic number, because the mean of its divisors is an integer number (2409951852).

Almost surely, 2^21420723890 is an apocalyptic number.

21420723890 is a deficient number, since it is larger than the sum of its proper divisors (17138505742).

21420723890 is a wasteful number, since it uses less digits than its factorization.

21420723890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107041.

The product of its (nonzero) digits is 48384, while the sum is 38.

The spelling of 21420723890 in words is "twenty-one billion, four hundred twenty million, seven hundred twenty-three thousand, eight hundred ninety".