21999977 has 2 divisors, whose sum is σ = 21999978. Its totient is φ = 21999976.

The previous prime is 21999973. The next prime is 22000001. The reversal of 21999977 is 77999912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19616041 + 2383936 = 4429^2 + 1544^2 .

It is a cyclic number.

It is not a de Polignac number, because 21999977 - 2² = 21999973 is a prime.

It is a Chen prime.

It is a plaindrome in base 11.

It is not a weakly prime, because it can be changed into another prime (21999973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999988 + 10999989.

It is an arithmetic number, because the mean of its divisors is an integer number (10999989).

Almost surely, 2^21999977 is an apocalyptic number.

It is an amenable number.

21999977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21999977 is an equidigital number, since it uses as much as digits as its factorization.

21999977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 642978, while the sum is 53.

The square root of 21999977 is about 4690.4133080146. The cubic root of 21999977 is about 280.2038354187.

The spelling of 21999977 in words is "twenty-one million, nine hundred ninety-nine thousand, nine hundred seventy-seven".