20921967 has 12 divisors (see below), whose sum is σ = 32968104. Its totient is φ = 12679920.

The previous prime is 20921959. The next prime is 20921981. The reversal of 20921967 is 76912902.

It is not a de Polignac number, because 20921967 - 2³ = 20921959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921947) 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, 105568 + ... + 105765.

It is an arithmetic number, because the mean of its divisors is an integer number (2747342).

Almost surely, 2^20921967 is an apocalyptic number.

20921967 is a deficient number, since it is larger than the sum of its proper divisors (12046137).

20921967 is a wasteful number, since it uses less digits than its factorization.

20921967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211350 (or 211347 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 20921967 is about 4574.0536726191. The cubic root of 20921967 is about 275.5502678907.

The spelling of 20921967 in words is "twenty million, nine hundred twenty-one thousand, nine hundred sixty-seven".