21490400 has 36 divisors (see below), whose sum is σ = 52465392. Its totient is φ = 8595840.

The previous prime is 21490393. The next prime is 21490423. The reversal of 21490400 is 409412.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 12632 + ... + 14231.

It is an arithmetic number, because the mean of its divisors is an integer number (1457372).

Almost surely, 2^21490400 is an apocalyptic number.

21490400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21490400 is an abundant number, since it is smaller than the sum of its proper divisors (30974992).

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

21490400 is a wasteful number, since it uses less digits than its factorization.

21490400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26883 (or 26870 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21490400 is about 4635.7739375427. The cubic root of 21490400 is about 278.0234957627.

Adding to 21490400 its reverse (409412), we get a palindrome (21899812).

The spelling of 21490400 in words is "twenty-one million, four hundred ninety thousand, four hundred".