21655498 has 4 divisors (see below), whose sum is σ = 32483250. Its totient is φ = 10827748.

The previous prime is 21655493. The next prime is 21655507. The reversal of 21655498 is 89455612.

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

It can be written as a sum of positive squares in only one way, i.e., 20766249 + 889249 = 4557^2 + 943^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21655498.

It is not an unprimeable number, because it can be changed into a prime (21655493) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5413873 + ... + 5413876.

Almost surely, 2^21655498 is an apocalyptic number.

21655498 is a deficient number, since it is larger than the sum of its proper divisors (10827752).

21655498 is a wasteful number, since it uses less digits than its factorization.

21655498 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10827751.

The product of its digits is 86400, while the sum is 40.

The square root of 21655498 is about 4653.5468193626. The cubic root of 21655498 is about 278.7336435267.

The spelling of 21655498 in words is "twenty-one million, six hundred fifty-five thousand, four hundred ninety-eight".