21300990 has 32 divisors (see below), whose sum is σ = 53346816. Its totient is φ = 5433120.

The previous prime is 21300989. The next prime is 21300997. The reversal of 21300990 is 9900312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21300990.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21300997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14746 + ... + 16125.

It is an arithmetic number, because the mean of its divisors is an integer number (1667088).

Almost surely, 2^21300990 is an apocalyptic number.

21300990 is an abundant number, since it is smaller than the sum of its proper divisors (32045826).

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

21300990 is a wasteful number, since it uses less digits than its factorization.

21300990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30904.

The product of its (nonzero) digits is 486, while the sum is 24.

The square root of 21300990 is about 4615.2995569085. The cubic root of 21300990 is about 277.2042787560.

It can be divided in two parts, 21 and 300990, that multiplied together give a triangular number (6320790 = T₃₅₅₅).

The spelling of 21300990 in words is "twenty-one million, three hundred thousand, nine hundred ninety".