21570340 has 24 divisors (see below), whose sum is σ = 49416192. Its totient is φ = 7843680.

The previous prime is 21570317. The next prime is 21570379. The reversal of 21570340 is 4307512.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48804 + ... + 49243.

It is an arithmetic number, because the mean of its divisors is an integer number (2059008).

Almost surely, 2^21570340 is an apocalyptic number.

21570340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21570340 is an abundant number, since it is smaller than the sum of its proper divisors (27845852).

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

21570340 is a wasteful number, since it uses less digits than its factorization.

21570340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98067 (or 98065 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21570340 is about 4644.3880113531. The cubic root of 21570340 is about 278.3677998441.

Adding to 21570340 its reverse (4307512), we get a palindrome (25877852).

The spelling of 21570340 in words is "twenty-one million, five hundred seventy thousand, three hundred forty".