21777146 has 4 divisors (see below), whose sum is σ = 32665722. Its totient is φ = 10888572.

The previous prime is 21777139. The next prime is 21777149. The reversal of 21777146 is 64177712.

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., 20349121 + 1428025 = 4511^2 + 1195^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21777149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5444285 + ... + 5444288.

Almost surely, 2^21777146 is an apocalyptic number.

21777146 is a deficient number, since it is larger than the sum of its proper divisors (10888576).

21777146 is a wasteful number, since it uses less digits than its factorization.

21777146 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10888575.

The product of its digits is 16464, while the sum is 35.

The square root of 21777146 is about 4666.5989756995. The cubic root of 21777146 is about 279.2545904782.

The spelling of 21777146 in words is "twenty-one million, seven hundred seventy-seven thousand, one hundred forty-six".