21693078 has 36 divisors (see below), whose sum is σ = 51429924. Its totient is φ = 6553800.

The previous prime is 21693053. The next prime is 21693097. The reversal of 21693078 is 87039612.

It is a super-2 number, since 2×21693078² = 941179266228168, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 65373 + ... + 65703.

It is an arithmetic number, because the mean of its divisors is an integer number (1428609).

Almost surely, 2^21693078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21693078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25714962).

21693078 is an abundant number, since it is smaller than the sum of its proper divisors (29736846).

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

21693078 is a wasteful number, since it uses less digits than its factorization.

21693078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681 (or 347 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21693078 is about 4657.5828495047. The cubic root of 21693078 is about 278.8947843908.

The spelling of 21693078 in words is "twenty-one million, six hundred ninety-three thousand, seventy-eight".