21490464 has 48 divisors (see below), whose sum is σ = 58871232. Its totient is φ = 6851328.

The previous prime is 21490459. The next prime is 21490517. The reversal of 21490464 is 46409412.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2659 + ... + 7074.

It is an arithmetic number, because the mean of its divisors is an integer number (1226484).

Almost surely, 2^21490464 is an apocalyptic number.

21490464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21490464 is an abundant number, since it is smaller than the sum of its proper divisors (37380768).

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

21490464 is a wasteful number, since it uses less digits than its factorization.

21490464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9769 (or 9761 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21490464 is about 4635.7808403763. The cubic root of 21490464 is about 278.0237717539.

Adding to 21490464 its reverse (46409412), we get a palindrome (67899876).

The spelling of 21490464 in words is "twenty-one million, four hundred ninety thousand, four hundred sixty-four".