21061724 has 12 divisors (see below), whose sum is σ = 37377648. Its totient is φ = 10382400.

The previous prime is 21061717. The next prime is 21061739. The reversal of 21061724 is 42716012.

It is a self number, because there is not a number n which added to its sum of digits gives 21061724.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36797 + ... + 37364.

It is an arithmetic number, because the mean of its divisors is an integer number (3114804).

Almost surely, 2^21061724 is an apocalyptic number.

It is an amenable number.

21061724 is a deficient number, since it is larger than the sum of its proper divisors (16315924).

21061724 is a wasteful number, since it uses less digits than its factorization.

21061724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74236 (or 74234 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21061724 is about 4589.3053940656. The cubic root of 21061724 is about 276.1624577413.

Adding to 21061724 its reverse (42716012), we get a palindrome (63777736).

The spelling of 21061724 in words is "twenty-one million, sixty-one thousand, seven hundred twenty-four".