21709257942 has 16 divisors (see below), whose sum is σ = 43549693632. Its totient is φ = 7214556360.

The previous prime is 21709257923. The next prime is 21709257943. The reversal of 21709257942 is 24975290712.

It is a junction number, because it is equal to n+sod(n) for n = 21709257891 and 21709257900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21709257943) 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, 5463588 + ... + 5467559.

It is an arithmetic number, because the mean of its divisors is an integer number (2721855852).

Almost surely, 2^21709257942 is an apocalyptic number.

21709257942 is an abundant number, since it is smaller than the sum of its proper divisors (21840435690).

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

21709257942 is a wasteful number, since it uses less digits than its factorization.

21709257942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10931483.

The product of its (nonzero) digits is 635040, while the sum is 48.

The spelling of 21709257942 in words is "twenty-one billion, seven hundred nine million, two hundred fifty-seven thousand, nine hundred forty-two".