21777764 has 24 divisors (see below), whose sum is σ = 38808000. Its totient is φ = 10692000.

The previous prime is 21777751. The next prime is 21777773. The reversal of 21777764 is 46777712.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86639 + ... + 86889.

It is an arithmetic number, because the mean of its divisors is an integer number (1617000).

Almost surely, 2^21777764 is an apocalyptic number.

It is an amenable number.

21777764 is a deficient number, since it is larger than the sum of its proper divisors (17030236).

21777764 is a wasteful number, since it uses less digits than its factorization.

21777764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 561 counting only the distinct ones).

The product of its digits is 115248, while the sum is 41.

The square root of 21777764 is about 4666.6651904760. The cubic root of 21777764 is about 279.2572320503.

The spelling of 21777764 in words is "twenty-one million, seven hundred seventy-seven thousand, seven hundred sixty-four".