20991402 has 24 divisors (see below), whose sum is σ = 46949760. Its totient is φ = 6771240.

The previous prime is 20991401. The next prime is 20991403. The reversal of 20991402 is 20419902.

It is an interprime number because it is at equal distance from previous prime (20991401) and next prime (20991403).

It is not an unprimeable number, because it can be changed into a prime (20991401) 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, 18252 + ... + 19367.

It is an arithmetic number, because the mean of its divisors is an integer number (1956240).

Almost surely, 2^20991402 is an apocalyptic number.

20991402 is an abundant number, since it is smaller than the sum of its proper divisors (25958358).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20991402 is a wasteful number, since it uses less digits than its factorization.

20991402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37658 (or 37655 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 20991402 is about 4581.6374802029. The cubic root of 20991402 is about 275.8547597521.

The spelling of 20991402 in words is "twenty million, nine hundred ninety-one thousand, four hundred two".