21551290 has 8 divisors (see below), whose sum is σ = 38792340. Its totient is φ = 8620512.

The previous prime is 21551273. The next prime is 21551297. The reversal of 21551290 is 9215512.

It can be written as a sum of positive squares in 2 ways, for example, as 19000881 + 2550409 = 4359^2 + 1597^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21551297) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1077555 + ... + 1077574.

Almost surely, 2^21551290 is an apocalyptic number.

21551290 is a deficient number, since it is larger than the sum of its proper divisors (17241050).

21551290 is a wasteful number, since it uses less digits than its factorization.

21551290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2155136.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 21551290 is about 4642.3366961047. The cubic root of 21551290 is about 278.2858282038.

The spelling of 21551290 in words is "twenty-one million, five hundred fifty-one thousand, two hundred ninety".