21698940 has 24 divisors (see below), whose sum is σ = 60757200. Its totient is φ = 5786368.

The previous prime is 21698933. The next prime is 21698993. The reversal of 21698940 is 4989612.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 180765 + ... + 180884.

It is an arithmetic number, because the mean of its divisors is an integer number (2531550).

Almost surely, 2^21698940 is an apocalyptic number.

21698940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21698940 is an abundant number, since it is smaller than the sum of its proper divisors (39058260).

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

21698940 is a wasteful number, since it uses less digits than its factorization.

21698940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361661 (or 361659 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 21698940 is about 4658.2121033719. The cubic root of 21698940 is about 278.9199035246.

The spelling of 21698940 in words is "twenty-one million, six hundred ninety-eight thousand, nine hundred forty".