21394540 has 12 divisors (see below), whose sum is σ = 44928576. Its totient is φ = 8557808.

The previous prime is 21394519. The next prime is 21394561. The reversal of 21394540 is 4549312.

It is an interprime number because it is at equal distance from previous prime (21394519) and next prime (21394561).

It is a zygodrome in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 21394499 and 21394508.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 534844 + ... + 534883.

It is an arithmetic number, because the mean of its divisors is an integer number (3744048).

Almost surely, 2^21394540 is an apocalyptic number.

21394540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21394540 is an abundant number, since it is smaller than the sum of its proper divisors (23534036).

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

21394540 is a wasteful number, since it uses less digits than its factorization.

21394540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1069736 (or 1069734 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21394540 is about 4625.4232238791. The cubic root of 21394540 is about 277.6094960583.

The spelling of 21394540 in words is "twenty-one million, three hundred ninety-four thousand, five hundred forty".