21478290 has 16 divisors (see below), whose sum is σ = 51547968. Its totient is φ = 5727536.

The previous prime is 21478277. The next prime is 21478291. The reversal of 21478290 is 9287412.

It is a happy number.

It is a super-2 number, since 2×21478290² = 922633882648200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21478291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 357942 + ... + 358001.

It is an arithmetic number, because the mean of its divisors is an integer number (3221748).

Almost surely, 2^21478290 is an apocalyptic number.

21478290 is an abundant number, since it is smaller than the sum of its proper divisors (30069678).

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

21478290 is a wasteful number, since it uses less digits than its factorization.

21478290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715953.

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21478290 is about 4634.4676069641. The cubic root of 21478290 is about 277.9712631821.

The spelling of 21478290 in words is "twenty-one million, four hundred seventy-eight thousand, two hundred ninety".