21078290 has 16 divisors (see below), whose sum is σ = 38004120. Its totient is φ = 8417280.

The previous prime is 21078289. The next prime is 21078307. The reversal of 21078290 is 9287012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 13890529 + 7187761 = 3727^2 + 2681^2 .

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, 6320 + ... + 9060.

Almost surely, 2^21078290 is an apocalyptic number.

21078290 is a deficient number, since it is larger than the sum of its proper divisors (16925830).

21078290 is a wasteful number, since it uses less digits than its factorization.

21078290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3517.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21078290 is about 4591.1098875980. The cubic root of 21078290 is about 276.2348435274.

The spelling of 21078290 in words is "twenty-one million, seventy-eight thousand, two hundred ninety".