21989949 has 16 divisors (see below), whose sum is σ = 29990400. Its totient is φ = 14327856.

The previous prime is 21989941. The next prime is 21989953. The reversal of 21989949 is 94998912.

It is a happy number.

It is not a de Polignac number, because 21989949 - 2³ = 21989941 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21989941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49872 + ... + 50310.

It is an arithmetic number, because the mean of its divisors is an integer number (1874400).

Almost surely, 2^21989949 is an apocalyptic number.

It is an amenable number.

21989949 is a deficient number, since it is larger than the sum of its proper divisors (8000451).

21989949 is a wasteful number, since it uses less digits than its factorization.

21989949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 784.

The product of its digits is 419904, while the sum is 51.

The square root of 21989949 is about 4689.3441972199. The cubic root of 21989949 is about 280.1612549029.

The spelling of 21989949 in words is "twenty-one million, nine hundred eighty-nine thousand, nine hundred forty-nine".