21340820 has 48 divisors (see below), whose sum is σ = 46545408. Its totient is φ = 8213760.

The previous prime is 21340811. The next prime is 21340859. The reversal of 21340820 is 2804312.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21340792 and 21340801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68465 + ... + 68775.

It is an arithmetic number, because the mean of its divisors is an integer number (969696).

Almost surely, 2^21340820 is an apocalyptic number.

21340820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21340820 is an abundant number, since it is smaller than the sum of its proper divisors (25204588).

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

21340820 is a wasteful number, since it uses less digits than its factorization.

21340820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21340820 is about 4619.6125378651. The cubic root of 21340820 is about 277.3769494754.

The spelling of 21340820 in words is "twenty-one million, three hundred forty thousand, eight hundred twenty".