21011000 has 32 divisors (see below), whose sum is σ = 49168080. Its totient is φ = 8404000.

The previous prime is 21010987. The next prime is 21011009. The reversal of 21011000 is 11012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (5).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011009) 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, 9506 + ... + 11505.

Almost surely, 2^21011000 is an apocalyptic number.

21011000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011000 is an abundant number, since it is smaller than the sum of its proper divisors (28157080).

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

21011000 is a wasteful number, since it uses less digits than its factorization.

21011000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21032 (or 21018 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 21011000 is about 4583.7757362245. The cubic root of 21011000 is about 275.9405809216.

Adding to 21011000 its reverse (11012), we get a palindrome (21022012).

The spelling of 21011000 in words is "twenty-one million, eleven thousand".