21106957 has 2 divisors, whose sum is σ = 21106958. Its totient is φ = 21106956.

The previous prime is 21106933. The next prime is 21106961. The reversal of 21106957 is 75960112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16859236 + 4247721 = 4106^2 + 2061^2 .

It is a cyclic number.

It is not a de Polignac number, because 21106957 - 2¹⁹ = 20582669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21106907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553478 + 10553479.

It is an arithmetic number, because the mean of its divisors is an integer number (10553479).

Almost surely, 2^21106957 is an apocalyptic number.

It is an amenable number.

21106957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106957 is an equidigital number, since it uses as much as digits as its factorization.

21106957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21106957 is about 4594.2308387803. The cubic root of 21106957 is about 276.3600155572.

The spelling of 21106957 in words is "twenty-one million, one hundred six thousand, nine hundred fifty-seven".