21009976 has 32 divisors (see below), whose sum is σ = 42638400. Its totient is φ = 9648000.

The previous prime is 21009973. The next prime is 21009983. The reversal of 21009976 is 67990012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21009973) 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, 27601 + ... + 28351.

It is an arithmetic number, because the mean of its divisors is an integer number (1332450).

Almost surely, 2^21009976 is an apocalyptic number.

21009976 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21009976 is an abundant number, since it is smaller than the sum of its proper divisors (21628424).

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

21009976 is a wasteful number, since it uses less digits than its factorization.

21009976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1039 (or 1035 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 21009976 is about 4583.6640365542. The cubic root of 21009976 is about 275.9360980675.

Adding to 21009976 its reverse (67990012), we get a palindrome (88999988).

The spelling of 21009976 in words is "twenty-one million, nine thousand, nine hundred seventy-six".