21999726 has 36 divisors (see below), whose sum is σ = 55450512. Its totient is φ = 6285384.

The previous prime is 21999721. The next prime is 21999727. The reversal of 21999726 is 62799912.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21999721) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11590 + ... + 13353.

It is an arithmetic number, because the mean of its divisors is an integer number (1540292).

Almost surely, 2^21999726 is an apocalyptic number.

21999726 is an abundant number, since it is smaller than the sum of its proper divisors (33450786).

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

21999726 is a wasteful number, since it uses less digits than its factorization.

21999726 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24965 (or 24955 counting only the distinct ones).

The product of its digits is 122472, while the sum is 45.

The square root of 21999726 is about 4690.3865512343. The cubic root of 21999726 is about 280.2027697898.

The spelling of 21999726 in words is "twenty-one million, nine hundred ninety-nine thousand, seven hundred twenty-six".