21977757 has 8 divisors (see below), whose sum is σ = 32559680. Its totient is φ = 14651820.

The previous prime is 21977743. The next prime is 21977771. The reversal of 21977757 is 75777912.

It is an interprime number because it is at equal distance from previous prime (21977743) and next prime (21977771).

It is not a de Polignac number, because 21977757 - 2¹⁶ = 21912221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21977777) 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, 406969 + ... + 407022.

It is an arithmetic number, because the mean of its divisors is an integer number (4069960).

Almost surely, 2^21977757 is an apocalyptic number.

21977757 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21977757 is a deficient number, since it is larger than the sum of its proper divisors (10581923).

21977757 is an equidigital number, since it uses as much as digits as its factorization.

21977757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814000 (or 813994 counting only the distinct ones).

The product of its digits is 216090, while the sum is 45.

The square root of 21977757 is about 4688.0440484279. The cubic root of 21977757 is about 280.1094682514.

The spelling of 21977757 in words is "twenty-one million, nine hundred seventy-seven thousand, seven hundred fifty-seven".