20991242 has 8 divisors (see below), whose sum is σ = 31598976. Its totient is φ = 10458252.

The previous prime is 20991241. The next prime is 20991263. The reversal of 20991242 is 24219902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (20991241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17978 + ... + 19109.

It is an arithmetic number, because the mean of its divisors is an integer number (3949872).

Almost surely, 2^20991242 is an apocalyptic number.

20991242 is a deficient number, since it is larger than the sum of its proper divisors (10607734).

20991242 is a wasteful number, since it uses less digits than its factorization.

20991242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37372.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20991242 is about 4581.6200191635. The cubic root of 20991242 is about 275.8540588798.

The spelling of 20991242 in words is "twenty million, nine hundred ninety-one thousand, two hundred forty-two".