21820464 has 30 divisors (see below), whose sum is σ = 61067396. Its totient is φ = 7273440.

The previous prime is 21820459. The next prime is 21820481. The reversal of 21820464 is 46402812.

It is a super-2 number, since 2×21820464² = 952265298350592, which contains 22 as substring.

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 5 ways as a sum of consecutive naturals, for example, 75622 + ... + 75909.

Almost surely, 2^21820464 is an apocalyptic number.

21820464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21820464 is an abundant number, since it is smaller than the sum of its proper divisors (39246932).

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

21820464 is a wasteful number, since it uses less digits than its factorization.

21820464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151545 (or 151536 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21820464 is about 4671.2379515499. The cubic root of 21820464 is about 279.4396275572.

The spelling of 21820464 in words is "twenty-one million, eight hundred twenty thousand, four hundred sixty-four".