21191490 has 32 divisors (see below), whose sum is σ = 56511360. Its totient is φ = 5650992.

The previous prime is 21191473. The next prime is 21191531. The reversal of 21191490 is 9419112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38974 + ... + 39513.

It is an arithmetic number, because the mean of its divisors is an integer number (1765980).

Almost surely, 2^21191490 is an apocalyptic number.

21191490 is an abundant number, since it is smaller than the sum of its proper divisors (35319870).

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

21191490 is a wasteful number, since it uses less digits than its factorization.

21191490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78503 (or 78497 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 21191490 is about 4603.4215535838. The cubic root of 21191490 is about 276.7284631561.

The spelling of 21191490 in words is "twenty-one million, one hundred ninety-one thousand, four hundred ninety".