20210978 has 4 divisors (see below), whose sum is σ = 30316470. Its totient is φ = 10105488.

The previous prime is 20210963. The next prime is 20211001. The reversal of 20210978 is 87901202.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19123129 + 1087849 = 4373^2 + 1043^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20210978.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5052743 + ... + 5052746.

Almost surely, 2^20210978 is an apocalyptic number.

20210978 is a deficient number, since it is larger than the sum of its proper divisors (10105492).

20210978 is a wasteful number, since it uses less digits than its factorization.

20210978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10105491.

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

The square root of 20210978 is about 4495.6621314329. The cubic root of 20210978 is about 272.3928956526.

The spelling of 20210978 in words is "twenty million, two hundred ten thousand, nine hundred seventy-eight".