21721914 has 12 divisors (see below), whose sum is σ = 47064186. Its totient is φ = 7240632.

The previous prime is 21721907. The next prime is 21721927. The reversal of 21721914 is 41912712.

It can be written as a sum of positive squares in only one way, i.e., 12006225 + 9715689 = 3465^2 + 3117^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 603369 + ... + 603404.

Almost surely, 2^21721914 is an apocalyptic number.

21721914 is an abundant number, since it is smaller than the sum of its proper divisors (25342272).

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

21721914 is a wasteful number, since it uses less digits than its factorization.

21721914 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1206781 (or 1206778 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 21721914 is about 4660.6774185734. The cubic root of 21721914 is about 279.0183053469.

The spelling of 21721914 in words is "twenty-one million, seven hundred twenty-one thousand, nine hundred fourteen".