20916961 has 12 divisors (see below), whose sum is σ = 23032380. Its totient is φ = 18982080.

The previous prime is 20916949. The next prime is 20916979. The reversal of 20916961 is 16961902.

It can be written as a sum of positive squares in 6 ways, for example, as 2383936 + 18533025 = 1544^2 + 4305^2 .

It is not a de Polignac number, because 20916961 - 2²¹ = 18819809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20916941) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9295 + ... + 11323.

It is an arithmetic number, because the mean of its divisors is an integer number (1919365).

Almost surely, 2^20916961 is an apocalyptic number.

It is an amenable number.

20916961 is a deficient number, since it is larger than the sum of its proper divisors (2115419).

20916961 is a wasteful number, since it uses less digits than its factorization.

20916961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2116 (or 2103 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 20916961 is about 4573.5064228664. The cubic root of 20916961 is about 275.5282891626.

The spelling of 20916961 in words is "twenty million, nine hundred sixteen thousand, nine hundred sixty-one".