21508494 has 32 divisors (see below), whose sum is σ = 51751680. Its totient is φ = 5821632.

The previous prime is 21508493. The next prime is 21508523. The reversal of 21508494 is 49480512.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21508493) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12679 + ... + 14274.

It is an arithmetic number, because the mean of its divisors is an integer number (1617240).

Almost surely, 2^21508494 is an apocalyptic number.

21508494 is an abundant number, since it is smaller than the sum of its proper divisors (30243186).

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

21508494 is a wasteful number, since it uses less digits than its factorization.

21508494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26984.

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21508494 is about 4637.7250888771. The cubic root of 21508494 is about 278.1015018484.

The spelling of 21508494 in words is "twenty-one million, five hundred eight thousand, four hundred ninety-four".