21649290 has 32 divisors (see below), whose sum is σ = 55956096. Its totient is φ = 5328960.

The previous prime is 21649289. The next prime is 21649307. The reversal of 21649290 is 9294612.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27366 + ... + 28145.

It is an arithmetic number, because the mean of its divisors is an integer number (1748628).

Almost surely, 2^21649290 is an apocalyptic number.

21649290 is an abundant number, since it is smaller than the sum of its proper divisors (34306806).

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

21649290 is a wasteful number, since it uses less digits than its factorization.

21649290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55534.

The product of its (nonzero) digits is 7776, while the sum is 33.

The square root of 21649290 is about 4652.8797534430. The cubic root of 21649290 is about 278.7070060444.

The spelling of 21649290 in words is "twenty-one million, six hundred forty-nine thousand, two hundred ninety".