21722542 has 4 divisors (see below), whose sum is σ = 32583816. Its totient is φ = 10861270.

The previous prime is 21722531. The next prime is 21722543. The reversal of 21722542 is 24522712.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5430634 + ... + 5430637.

It is an arithmetic number, because the mean of its divisors is an integer number (8145954).

Almost surely, 2^21722542 is an apocalyptic number.

21722542 is a deficient number, since it is larger than the sum of its proper divisors (10861274).

21722542 is a wasteful number, since it uses less digits than its factorization.

21722542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10861273.

The product of its digits is 2240, while the sum is 25.

The square root of 21722542 is about 4660.7447902669. The cubic root of 21722542 is about 279.0209942108.

The spelling of 21722542 in words is "twenty-one million, seven hundred twenty-two thousand, five hundred forty-two".