21739946 has 4 divisors (see below), whose sum is σ = 32609922. Its totient is φ = 10869972.

The previous prime is 21739943. The next prime is 21739951. The reversal of 21739946 is 64993712.

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., 19669225 + 2070721 = 4435^2 + 1439^2 .

It is not an unprimeable number, because it can be changed into a prime (21739943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5434985 + ... + 5434988.

Almost surely, 2^21739946 is an apocalyptic number.

21739946 is a deficient number, since it is larger than the sum of its proper divisors (10869976).

21739946 is a wasteful number, since it uses less digits than its factorization.

21739946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10869975.

The product of its digits is 81648, while the sum is 41.

The square root of 21739946 is about 4662.6115000073. The cubic root of 21739946 is about 279.0954910947.

The spelling of 21739946 in words is "twenty-one million, seven hundred thirty-nine thousand, nine hundred forty-six".