21533780 has 24 divisors (see below), whose sum is σ = 45571680. Its totient is φ = 8546720.

The previous prime is 21533737. The next prime is 21533789. The reversal of 21533780 is 8733512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1490 + ... + 6729.

It is an arithmetic number, because the mean of its divisors is an integer number (1898820).

Almost surely, 2^21533780 is an apocalyptic number.

21533780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21533780 is an abundant number, since it is smaller than the sum of its proper divisors (24037900).

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

21533780 is a wasteful number, since it uses less digits than its factorization.

21533780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8359 (or 8357 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21533780 is about 4640.4504091737. The cubic root of 21533780 is about 278.2104405259.

The spelling of 21533780 in words is "twenty-one million, five hundred thirty-three thousand, seven hundred eighty".