21213960 has 64 divisors (see below), whose sum is σ = 67392000. Its totient is φ = 5323776.

The previous prime is 21213947. The next prime is 21213971. The reversal of 21213960 is 6931212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21213960.

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, 3160 + ... + 7239.

It is an arithmetic number, because the mean of its divisors is an integer number (1053000).

Almost surely, 2^21213960 is an apocalyptic number.

21213960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21213960 is an abundant number, since it is smaller than the sum of its proper divisors (46178040).

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

21213960 is a wasteful number, since it uses less digits than its factorization.

21213960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10430 (or 10426 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 21213960 is about 4605.8614829367. The cubic root of 21213960 is about 276.8262365566.

The spelling of 21213960 in words is "twenty-one million, two hundred thirteen thousand, nine hundred sixty".