21689490 has 16 divisors (see below), whose sum is σ = 52054848. Its totient is φ = 5783856.

The previous prime is 21689471. The next prime is 21689497. The reversal of 21689490 is 9498612.

It is not an unprimeable number, because it can be changed into a prime (21689497) 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, 361462 + ... + 361521.

It is an arithmetic number, because the mean of its divisors is an integer number (3253428).

Almost surely, 2^21689490 is an apocalyptic number.

21689490 is an abundant number, since it is smaller than the sum of its proper divisors (30365358).

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

21689490 is a wasteful number, since it uses less digits than its factorization.

21689490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722993.

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 21689490 is about 4657.1976552429. The cubic root of 21689490 is about 278.8794072943.

The spelling of 21689490 in words is "twenty-one million, six hundred eighty-nine thousand, four hundred ninety".