21953977 has 4 divisors (see below), whose sum is σ = 21969700. Its totient is φ = 21938256.

The previous prime is 21953969. The next prime is 21953989. The reversal of 21953977 is 77935912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13682601 + 8271376 = 3699^2 + 2876^2 .

It is a cyclic number.

It is not a de Polignac number, because 21953977 - 2³ = 21953969 is a prime.

It is a super-2 number, since 2×21953977² = 963954212233058, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21953677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5538 + ... + 8635.

It is an arithmetic number, because the mean of its divisors is an integer number (5492425).

Almost surely, 2^21953977 is an apocalyptic number.

It is an amenable number.

21953977 is a deficient number, since it is larger than the sum of its proper divisors (15723).

21953977 is a wasteful number, since it uses less digits than its factorization.

21953977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15722.

The product of its digits is 119070, while the sum is 43.

The square root of 21953977 is about 4685.5071230337. The cubic root of 21953977 is about 280.0084053599.

The spelling of 21953977 in words is "twenty-one million, nine hundred fifty-three thousand, nine hundred seventy-seven".