21723630 has 16 divisors (see below), whose sum is σ = 52136784. Its totient is φ = 5792960.

The previous prime is 21723589. The next prime is 21723641. The reversal of 21723630 is 3632712.

It is a super-2 number, since 2×21723630² = 943832200753800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21723630.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 362031 + ... + 362090.

It is an arithmetic number, because the mean of its divisors is an integer number (3258549).

Almost surely, 2^21723630 is an apocalyptic number.

21723630 is an abundant number, since it is smaller than the sum of its proper divisors (30413154).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21723630 is a wasteful number, since it uses less digits than its factorization.

21723630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 724131.

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 21723630 is about 4660.8615083480. The cubic root of 21723630 is about 279.0256525019.

The spelling of 21723630 in words is "twenty-one million, seven hundred twenty-three thousand, six hundred thirty".