21077830 has 16 divisors (see below), whose sum is σ = 39164544. Its totient is φ = 8159040.

The previous prime is 21077803. The next prime is 21077831. The reversal of 21077830 is 3877012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21077831) 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, 33687 + ... + 34306.

It is an arithmetic number, because the mean of its divisors is an integer number (2447784).

Almost surely, 2^21077830 is an apocalyptic number.

21077830 is a deficient number, since it is larger than the sum of its proper divisors (18086714).

21077830 is a wasteful number, since it uses less digits than its factorization.

21077830 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68031.

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21077830 is about 4591.0597905059. The cubic root of 21077830 is about 276.2328340514.

The spelling of 21077830 in words is "twenty-one million, seventy-seven thousand, eight hundred thirty".