21059977 has 2 divisors, whose sum is σ = 21059978. Its totient is φ = 21059976.

The previous prime is 21059947. The next prime is 21060001. The reversal of 21059977 is 77995012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12702096 + 8357881 = 3564^2 + 2891^2 .

It is a cyclic number.

It is not a de Polignac number, because 21059977 - 2⁷ = 21059849 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21059947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10529988 + 10529989.

It is an arithmetic number, because the mean of its divisors is an integer number (10529989).

Almost surely, 2^21059977 is an apocalyptic number.

It is an amenable number.

21059977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21059977 is an equidigital number, since it uses as much as digits as its factorization.

21059977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39690, while the sum is 40.

The square root of 21059977 is about 4589.1150563044. The cubic root of 21059977 is about 276.1548219442.

The spelling of 21059977 in words is "twenty-one million, fifty-nine thousand, nine hundred seventy-seven".