21398020542 has 24 divisors (see below), whose sum is σ = 47122419240. Its totient is φ = 7015744080.

The previous prime is 21398020519. The next prime is 21398020573. The reversal of 21398020542 is 24502089312.

It is a happy number.

21398020542 is a `hidden beast` number, since 2 + 1 + 3 + 98 + 0 + 20 + 542 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21398020497 and 21398020506.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9742992 + ... + 9745187.

It is an arithmetic number, because the mean of its divisors is an integer number (1963434135).

Almost surely, 2^21398020542 is an apocalyptic number.

21398020542 is an abundant number, since it is smaller than the sum of its proper divisors (25724398698).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21398020542 is a wasteful number, since it uses less digits than its factorization.

21398020542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19488248 (or 19488245 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21398020542 in words is "twenty-one billion, three hundred ninety-eight million, twenty thousand, five hundred forty-two".