21999242 has 4 divisors (see below), whose sum is σ = 32998866. Its totient is φ = 10999620.

The previous prime is 21999221. The next prime is 21999269. The reversal of 21999242 is 24299912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18498601 + 3500641 = 4301^2 + 1871^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21999196 and 21999205.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5499809 + ... + 5499812.

Almost surely, 2^21999242 is an apocalyptic number.

21999242 is a deficient number, since it is larger than the sum of its proper divisors (10999624).

21999242 is a wasteful number, since it uses less digits than its factorization.

21999242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10999623.

The product of its digits is 23328, while the sum is 38.

The square root of 21999242 is about 4690.3349560559. The cubic root of 21999242 is about 280.2007149289.

The spelling of 21999242 in words is "twenty-one million, nine hundred ninety-nine thousand, two hundred forty-two".